Learn Russian: В какое время начинается сериал? В 20:40. - At what time does the TV series begin? At 20:40.

We use в plus the accusative case to say 'at' a certain time. Because время (time) is a neuter noun, its accusative form looks exactly like its dictionary form, so какое время doesn't change its spelling here.

How do you say 'В 20:40' out loud in Russian?

You say В двадцать сорок. In this everyday digital format, you just read the numbers for the hours and minutes exactly as they are written. You don't need to add the words for 'hours' or 'minutes'.

Why does the verb начинается end in -ся?

The -ся makes the verb reflexive, meaning the action happens to the subject itself. If you used начинает (without -ся), it would mean the TV series is starting something else. Because the series is simply 'beginning' on its own, it needs the reflexive ending.

Could I ask this using во сколько instead?

Yes, absolutely! Во сколько начинается сериал? is actually the most common, conversational way to ask 'At what time does the series begin?'. В какое время is just slightly more formal, but both mean the exact same thing.