"What are you doing?" is a common way to ask someone what they are currently doing in English. This phrase is derived from the verb "to do," which is used to describe an activity or action. Some example sentences using this phrase include:

"What are you doing this weekend?"

"What are you doing with that pencil?"

"What are you doing here?"

You can also use the present continuous tense to ask someone what they are currently doing. For example:

"What are you doing right now?"

"What are you doing tomorrow?"

In this case, "are" is the present tense of the verb "to be," and "doing" is the present participle of the verb "to do." This construction is used to describe ongoing or temporary actions or activities.