water and the water are not the same, that's why are acqua and l'acqua

I translated I drink water to Io bevo l'acqua. It says it is wrong. But in another exercise, he drink water, lui beve l'acqua is correct.

Btw, what's the difference between bevi and beve in pronounce?

That's because in this sentence, the amount of water is not precise. It's called "articolo partitivo" (or partitive article). You can find more info on internet. Sorry, but I can't explain it to you good enough

It makes no difference. It's the same as in how in english both 'To drink the water' and 'To drink water' are correct.

Io bevo acqua translates as "I drink water" ( not THE water, no definite article is indicated).
Tu bevi l'acqua translates to you (informal) drink THE water. Beve l'acqua translates to 'you (formal) drink THE water. L' indicates a definite article is needed.

I think in Italian you can't put those two vowels together. Then it would be "la acqua" So because of that there is an apostrophe. The "la" makes it "the water" but without the l' it would just be water.

it's water and THE water

l'acqua and acqua are not the same, l'acqua means 'the water' and acqua means 'water'