Learn French: Le matériel coûte très cher, alors faites attention ! - The equipment is very expensive, so pay attention!

In the expression coûter cher (to be expensive), the word cher functions as an adverb modifying the verb coûte, not as an adjective modifying the noun. Since adverbs are invariable in French, cher will never take an -e or -s here, even if the subject were feminine or plural.

Why translate coûte très cher as 'is very expensive' rather than 'costs very expensive'?

English naturally uses the verb 'to be' for 'is expensive' and 'to cost' for 'costs a lot'. French combines the verb coûter (to cost) with cher (dearly), so 'is very expensive' is the most natural English equivalent for this French structure.

Is matériel countable in French, since it means 'equipment'?

Yes! While 'equipment' is uncountable in English, French treats le matériel as a regular noun that can be singular or plural. Here, used in the singular, it refers to the equipment or hardware as a collective whole.

Why is 'pay attention' translated using faites instead of the verb for 'to pay'?

In French, the fixed expression for 'to pay attention' or 'to be careful' is faire attention. You can never use the French verb payer (to pay) for this meaning. Here, faites is the imperative (command) form directed at vous.