When you look up a Latin verb in the dictionary, you see two forms.
For example: dormiō, dormīre
The first form (dormiō) is the 1st person singular form. It is translated as "I sleep" or "I am sleeping".
The second form (dormīre) is called the infinitive. It is translated as "to sleep."
Infinitives are used to complete the idea of certain verbs. For example, it is not very meaningful to say "I am able" or "we want." What am I able to do? What do we want to do?
Here are some verbs that almost always have infinitives with them:
possum, possum: to be able
volō, velle: to want
nōlō, nōlle: to not want
translate: nōs in īnsula habitāre volumus.
translate: equus currere potest.
translate: pater dīcere nōn vult.
There are other verbs that sometimes have infinitives with them.
parō, parāre: to prepare
cupiō, cupere: to want, desire
timeō, timēre: to fear, be afraid
translate: Sabīna cibum parat.
translate: Sabīna dormīre parat.
translate: canis dominum timet.
translate: canis in viā ambulāre timet.
translate: ego vīnum cupiō.
vocabulary help:
cupiō, cupere: to want, desire
translate: ego bibere cupiō.
vocabulary help:
cupiō, cupere: to want, desire
bibō, bibere: to drink
translate: difficile est in popīnā labōrāre.
vocabulary help:
difficile: difficult
translate: perīculōsum est in Subūrā nocte ambulāre.
vocabulary help:
nocte: at night
perīculōsum: dangerous