Learn Hardcore Swahili: Tafadhali, uliza swali lingine.

Tafadhali, uliza swali lingine. = Please, ask another question.
Tafadhali is very common in polite requests.
Depending on context, tafadhali can also appear in expressions connected with politeness more generally, but here it simply means please.

Why is it uliza and not kuuliza?

Kuuliza is the infinitive form, meaning to ask.

When Swahili gives a direct command to one person, it often uses the imperative form, which here is uliza.

So:

In this sentence, the speaker is telling someone to do something, so the imperative uliza is used.

Is uliza a command to one person or more than one person?

Here, uliza is normally understood as a command to one person.

If you were telling more than one person to ask another question, you would usually say:

So: