Learn Spanish (Latin America): Las niñas jugaban con la pelota y las muñecas. - The girls used to play with the ball and the dolls.

Jugaban is in the imperfect tense, which we use to talk about past habits, ongoing actions, or how things used to be. Because the sentence means the girls used to play over an extended period of time, rather than a single completed event, the imperfect is the right choice.

In the present tense, the verb changes to juegan. Why isn't there an 'e' in jugaban?

That is one of the great things about the imperfect tense! Verbs that have stem changes in the present tense (like the u changing to ue in juegan) are completely regular in the imperfect. You just take the pure stem jug- and add the regular ending.

What exactly does the -aban ending in jugaban tell us?

For regular -ar verbs like jugar, the ending -aban tells you two things: it is in the imperfect tense (past habits or descriptions), and the subject is they (ellos/ellas) or you all (ustedes). Here, it matches las niñas (they).

Why is it y las muñecas instead of just y muñecas?