Learn Swedish: Du kan be om vad som helst under mötet. - You can ask for anything during the meeting.

The phrase som helst is added after question words to create "any" or "-ever" expressions. Vad means "what", and adding som helst turns it into "anything" or "whatever". You can do this with other question words too, like vem som helst (anyone) or var som helst (anywhere).

Is vad som helst treated as a single unit in the sentence structure?

Yes, grammatically the three words vad som helst stick together and act as a single indefinite pronoun. In this sentence, the whole phrase acts as the object of the preposition om, exactly how a normal noun would.

Why do we use be om here instead of fråga for the word "ask"?

In Swedish, you choose the verb based on what you are asking. Use fråga when you are asking a question to get information. Use be om when you are making a request for a physical thing, an action, or a favor. Since you are requesting a thing ("anything"), be om is the correct choice.

Wait, doesn't under mean "underneath"? Why does it mean "during" here?

Under is a very versatile preposition. When referring to physical space, it means "under" or "beneath". But when used with an event or a block of time, like mötet (the meeting) or sommaren (the summer), it translates to "during".