Learn Swedish: Han frågar mig ofta.

Even though it is spelled mig, it is almost always pronounced like the English word "may". You will sometimes even see it written as mej in very informal text messages, but mig is the standard spelling.

Why is ofta at the end of the sentence?

In Swedish, time adverbs like ofta (often) usually come after the verb and the object. So instead of the English word order "He often asks me," Swedish uses "He asks me often" (Han frågar mig ofta).

When do I use mig instead of jag?

Just like in English, Swedish has different pronouns depending on whether the person is doing the action or receiving it. You use jag (I) when you are doing the action, but you use mig (me) when the action is happening to you, like being asked a question.

If I change "he" to "they", does the verb frågar change?

No, Swedish verbs never change based on who is doing the action! If it were "They ask me often", it would simply be De frågar mig ofta. The verb frågar stays exactly the same.