There is no change in meaning, but if a person does not include "de" correctly it may sound awkward.
When we learn verbs, it is always worth learning their prepositions. Some of them are the same for Portuguese and English, for example, lidar COM = deal WITH. Others may change: se preocupar COM = worry ABOUT.
Some Portuguese verbs require prepositions depending on the usage, but they keep the same meaning ("precisar" is an example of that) and others have the meaning changed if you add a preposition. But that's a thing you'll learn through exercises. I won't fill you up with all that stuff ;)
^That is true of all languages, and you pretty much just have to memorize them.
An example from English. A friend of mine asked for help filling a form. He was holding a piece of paper, and we said, "Oh, fill out the form?" He said, "Why fill out? Why not fill in or fill down or fill up or fill under?"
Notice that fill in could also have worked, though it changes the meaning slightly, but fill up means something quite different, and just "fill" doesn't make sense in this sentence. Yet you can fill a bucket of paint...
I think that is the most complex verb + preposition I have come across, and it's in my own language! lol I'd never have noticed if he hadn't asked about it.
Just a small note: these are known as phrasal verbs in English grammar, and they're not exactly the same as verb + preposition collocations.
You can tell the difference by using the object pronoun "it": if it's a verb + preposition, the position of the latter will be before (pre-) the word "it". If it's a phrasal verb, the "it" will come first. For example:
- You can walk off the platform. You can walk off it. (verb + preposition collocation)
- You can walk off a headache. You can walk it off. (phrasal verb)
With some phrasal verbs, a real noun phrase can come in between too, and with some it's even preferable:
- You can put your hat on. Or you can put on your hat. (both are okay)
- You can take a person out on a date. But you will face a criminal court if you take out a person on a date. (here you have two different phrasal verbs that look the same, but they go in different places and mean different things.)
This was going to be a small note, but I got carried away. :p
It has meaning in Portuguese, apparently. It goes with the verb (similar to the personal a in Spanish, since you also study Spanish). Just use it and don't worry too much about its meaning. When translating from one language to another, each word does not always correspond with another. Just use it.
Nós precisamos você = We make you precise/accurate
I know, it's also weird in Portuguese. The thing is, we also have precisar in the sense of to make something/someone precise, but it's seldom used in this sense. Unlike precisar in the sense of to need, it doesn't need any preposition.
Você poderia precisar melhor as suas palavras? = Could you make your words more precise? (be clearer)
But, unlike the verb, we use the noun precisão (precision) and the adjective preciso(s)/precisa(s) (precise) very often.