"I have coffee ice cream."
Translation:Ho il gelato al caffè.
It is not wrong, this is just highly ambiguous. If it is meant to say "I will have" in an ordering context you wouldn't use the verb avere (to have), you would use prendere (to take). For example "prendo un gelato al caffè" (I take a coffee ice cream) or "voglio prendere un gelato al cafè" (I want to take a coffee ice cream). The verb to have (avere) is not used in these contexts as it is in english. It thus depends on whether this sentence was intended to be a statement "ho un gelato al caffè" (I have a coffee ice cream) or a request "ho il gelato al caffè" (I have the coffee ice cream), but the second is just wrong and you would not use it in any context (source: my fiancé is Italian, native speaker). On a side note... "ho un gelato al caffè" can also mean "I have an ice cream at the cafè", while technically correct, is not used anymore, so just watch out for that. Also, I noticed that most people are using "io" and I just wanted you let you all know that it is not necessary and not used in spoken Italian (just like tu, lui/lei, voi, noi and loro). You can just use the conjugated verb (eg. ho, hai, ha, avete, abbiamo, hanno). I hope this helps!
In everyday situations when we are refering to a specific object we use article (Io ho il pane- I have a certain bread) while when refering generaly to a thing we don't use it. I guess it is difficult for english speakers because you don't use articles. Let me explain it better: -Give me the bread- i think it is translated in italian as "Dammi il pane", you will use this sentence when you are sitting in the table and you are asking your friend to give you the bread you have on your table. While- Give me bread- "Dammi pane", you will say that in a grocery shop, you want bread in general.
"ho" is conjugated from the verb "to have: avere".
And, unlike in English, a verb gives out quite a lot of information. Just by looking at it you'll know who the text speaks of - "ho" tells that it's YOU (as in first person singular), so you don't need to type out "io".
simple chart: -http://iltavoloitaliano.com/learning_avere_present_tense/
"al" in this case can be treated as "with", like "made with". It works the same way in French. In English, you're used to prepositions having set meanings, in Romance languages like Italian and French, that's not the case. The meanings cover multiple things that we express differently in English. It's something you will have to get used to when learning a new language. Throw away your English mind.