Anybody could help with Spanish?

What does it mean to conjugate a verb? how do you conjugate verbs in spanish?

Question 10 (fill-in-the-blank worth 1 points) susana cruza la calle en el paso de answer for blank 1:

Which phrase best completes this sentence? en los almacenes están al aire libre. a. el supermercado b. el mall c. la feria artesanal d. la librería