f.formica: I agree that 'entrare' is intransitive and can't be used with a direct object, but it's counterpart 'enter' in English can, which might be the cause of some users' confusion: "Please enter your names in the space provided," is just one example of a transitive use in English.
Lightz1. Start by reviewing the difference between transitive and intransitive verbs. You can find that distinction explained on a number of online sites. Verbs are usually, though not always the same in various languages. Transitive verbs are those that can "take" a direct object. Think of them as verbs that combine with a noun or pronoun object to 'complete their meaning'. Examples are verbs such as buy, sell, eat, break, build, etc etc meaning they combine with direct objects to complete their meaning. If one said: I bought. You'd ask: what did you buy? That "what" is a direct object. The same with 'I built" or I broke" " I sold" etc. they require direct objects. Of course you can also say "I ate" and leave it at that, but one might still ask, well what did you eat. On the other hand, intransitive verbs cannot 'take' a direct object: usually though not always verbs of motion: I came e.g., you can't 'come' anything. It's intransitive. To die, and to be born since you can't die or born anything. I fell asleep also intransitive since you can't fall anything asleep. Now some verbs may be both: and so in Italian at least the auxiliary would be 'essere' if the verb's being used intransitively, i.e., without a direct object or 'avere' if it's being used transitively, with a direct object. "Esplodere" is a good example: If I said, "The bombs exploded at 5 o'clock" I'd be using the verb intransitively and so I'd use 'essere": "Le bombe sono esplose alle 5." If on the other hand I said, "They blew up the house," then I'd use 'avere' as the auxiliary since house is the direct object. You'd ask: What did they blow up? Ans. the house, so "Hanno esploso la casa." Best though is to look up other examples of transitive/intransitive verbs online, preferably one with italian examples since though similar no two languages are exactly alike in this regard.
allintolearning: "She goes into.../she comes into..." are both correct and so I agree with you (and csryder88) on them, but "she enters into..." is incorrect, though I don't think that's what you were implying in response to csryder88. One doesn't 'enter into" a location, one simply 'enters it'. That said, one can "enter into" an agreement, a contract, etc.
I want to ask "She gets what in the restaurant?", but I bet some people actually might say "She gets into the restaurant just in time." (The police car came by and she was not noticed.) or (Everyone is here for the birthday dinner.) It is colloquial and would be used more for "getting into a car." where it is not a simple matter of walking into a place. The best translation is "enters" which includes "into" in the verb. "She enters the restaurant." and the next best would be "She comes into the restaurant." as seen by someone in the restaurant, while "She goes into the restaurant." would be from the viewpoint of someone outside the restaurant. If she "gets into" a place, there is some reason that we are noticing it that way. There is more effort involved than just entering the restaurant, whether it be by a certain time or without being stopped.
"enter" includes the idea of "into" so the preposition is unnecessary and sounds unnatural. In other words the verb is used with a direct object and without a preposition. Other verbs of motion require 'into' because they can't be used with a direct object alone: she walked into the room; she goes into the store; he ran into the building, they sailed into the harbor, etc. You can't express these sentences without the preposition 'into', but with 'enter' you do.
That was probably a slightly different exercise for "She is in a restaurant." would be "Lei entra in un ristorante.", but when you have "the restaurant" or "il ristorante":
in Italian they contract "in" + "il" = "nel".
http://italian.about.com/library/fare/blfare153a.htm Italian prepositions
Ella is an Italian nominative form that is now used as a literary form and this form is used only for people. Lei is used to replace all feminine nouns, not just people and is not just a literary form, but is originally an object form which became used also as nominative form in the spoken language and now can also be seen in written language. There are two object forms Tonic (strong) and atonic (weak or unstressed form). Of course, "lei", "lui" and "loro" are Tonic forms and are the ones that are so often used as subjects.
Context. If you're talking to someone, in that person's face, it's You. If you and another person or you and other people are talking about a woman, it's she. No one speaks in isolated sentences like this. Know it can mean both and wait for the specific situation to arise to tell you which one it is.
In English, the verb 'enter' cannot be used with just 'to'; it must be used with either a direct object without any preposition at all: She entered the restaurant" OR it must be used with the preposition "into" as e.g. "She entered into an agreement with the team." The preposition "on" is also possible: "She entered on the 2nd floor." Perhaps even 'onto' as in "She entered onto the balcony from the bedroom." But "enters to" is incorrect.