Learn Italian: Vengo volentieri al concerto con te. - I gladly come to the concert with you.

Venire (to come) is an irregular verb. While a regular -ire verb would just drop the ending and add -o for the 'I' form, venire adds a 'g' to become vengo (I come). Because it is irregular, you simply have to memorize this form. Notice that we don't need to say io vengo because the verb ending already makes it clear who is coming.

How does the word volentieri work in this sentence?

Volentieri is an adverb that means gladly, willingly, or with pleasure. In English you might say 'I gladly come,' but in Italian, adverbs that describe how an action is done usually go right after the verb. That is why it is placed immediately after vengo.

Why do we use al instead of just a for 'to the'?

In Italian, when the preposition a (to or at) is followed by the definite article il (the), they mash together into one word. Since concerto is a masculine singular noun, it takes the article il. Therefore, a plus il combines to become al.

Why does it say con te instead of con tu?