Learn Italian: Vado a letto presto stasera. - I am going to bed early tonight.

It is very tempting to translate "I am" to sto, but in Italian, the simple present verb vado already means both "I go" and "I am going". You do not use stare to translate the English present continuous ("am doing something") when using verbs of movement like andare (to go). Just use the regular present tense!

Why is it a letto instead of al letto?

Just like in English, "going to bed" is a set phrase. Italians say andare a letto (to go to bed) without using the definite article for "the" (il). If you said al letto (to the bed), it would sound like you are just walking over to a piece of furniture rather than actually going to sleep.

Does presto mean "early" or "soon"?

It can mean both! In this sentence, because it describes when you are going to bed, it means "early". In other common contexts, such as the farewell A presto! (See you soon!), it translates to "soon".

Where does the word stasera come from?

Stasera is a contraction that has become its own everyday word. It comes from squeezing together questa (this) and sera (evening). It is the most natural and common way to say "tonight" or "this evening" in Italian.