Learn Hardcore Japanese: niku ha takasugiru.

The particle は marks 肉 (meat) as the topic of the sentence. It literally means “As for meat…,” so you’re stating your opinion about meat’s price rather than simply introducing a new subject.

Why is 肉 marked with は instead of が?

While が is the subject marker used to present new or focal information, は sets up a topic or contrast.

肉が高すぎる feels like “I’ve just realized that meat is too expensive.”
肉は高すぎる feels like “(Compared to other things or in general) meat is too expensive.”

What does 高すぎる literally mean and how is it formed?

高すぎる comes from the adjective 高い (high/expensive) plus すぎる (to exceed/too much).
Literally it’s “exceeds high,” so it translates as “too high” or “too expensive.”

How do you attach すぎる to an い-adjective like 高い?

You drop the final い of the adjective and add すぎる:
高い → 高- + すぎる = 高すぎる.
(Note: The irregular adjective いい becomes 良すぎる.)