Learn Russian: Что ты думаешь?

The letter ч normally makes a "ch" sound, but the word что is a famous exception! It is always pronounced as "shto". You just have to memorize this one.

How do we make the ты (you) form for verbs like думать (to think)?

Думать is a regular first conjugation verb, meaning it ends in -ать. To use it with ты (informal you), you drop the final -ть from the dictionary form and replace it with the ending -ешь. That gives us думаешь.

Why isn't there a word for "do" in the Russian sentence?

Russian doesn't use helper verbs like "do" or "does" to form questions. Instead, you just literally ask "What you think?" (Что ты думаешь?) and let the question word and your tone of voice show that it is a question.

Could this also translate to "What are you thinking?"

Yes! Russian doesn't have a separate tense for things happening right now (like "are thinking"). A present tense verb like думаешь covers both "do you think" (in general) and "are you thinking" (right at this exact moment).