Parasolka chroni nie tylko przed deszczem; latem daje też trochę cienia.

Both words exist, but they usually mean different things:

• parasolka = a handheld umbrella
• parasol = a sunshade, beach umbrella, patio umbrella, or sometimes a formal/literary word for umbrella

In everyday Polish, if you mean the thing you carry when it rains, parasolka is the normal word.

Chroni is the 3rd person singular form of chronić, meaning to protect.

So:

• parasolka chroni = the umbrella protects

It agrees with parasolka, which is singular and feminine. In the present tense, Polish verbs agree with the subject in person and number, but not in gender in this form.