Learn Italian: L'insegnante finisce la lezione tardi. - The teacher finishes the lesson late.

Finire (to finish) is an -ire verb that needs a special group of letters, -isc-, inserted before the ending. For the "he/she/it" form (which matches l'insegnante), we take the stem fin-, add -isc-, and then add the regular ending -e to get finisce.

Is l'insegnante masculine or feminine?

It can be either! Words ending in -ante are often used for both men and women. Because the word starts with a vowel, it takes the article l' in both cases. You would only know the gender from context or by looking at adjectives, like l'insegnante bravo (male) or l'insegnante brava (female).

Why is it la lezione if the word ends in -e? Shouldn't feminine words end in -a?

While most feminine words end in -a, many Italian words end in -e. These can be masculine or feminine, which you just have to memorize. However, a helpful trick is that words ending in -zione, like lezione (lesson) or stazione (station), are almost always feminine. That is why it uses the feminine article la.

Tardi ends in an -i. Does this mean it is plural?