Learn Russian: Она очень милая.

In Russian, the present tense of the verb "to be" (am, is, are) is almost never used. You simply put the subject (Она) and the description (очень милая) right next to each other.

Why does милая end in -ая?

Милая is an adjective, and in Russian, adjectives must match the gender of the person or thing they describe. Since Она (she) is feminine, the adjective takes the standard feminine ending -ая.

How would I say "He is very sweet" to see the masculine form?

You would say Он очень милый. The pronoun changes to Он (he), and the adjective changes to its masculine form, taking the -ый ending.

Can милая mean anything else besides "sweet"?

Yes! Depending on the context, милая can also mean "cute," "nice," or "lovely." It is a very common word used to describe someone with a pleasant personality, a nice interaction, or a cute animal.