Learn Spanish (Latin America): La peluquería está cerrada el martes.

We use está (from the verb estar) because being closed is a temporary state or the result of an action. If we used es (from the verb ser), it would imply that being closed is a permanent, defining characteristic of the salon.

Why does the sentence use cerrada instead of cerrado?

In this sentence, cerrada acts as an adjective describing la peluquería (the hair salon). Because peluquería is a feminine, singular noun, the adjective must match it exactly by taking the feminine singular ending -a.

How do we know "on" is part of the translation if there is no Spanish word for "on" here?

In Spanish, you never use prepositions like en to say "on a certain day." Instead, you simply use the definite article (el or los) right before the day of the week. So, el martes directly translates to "on Tuesday."

Does el martes mean it is closed every Tuesday, or just this Tuesday?

Strictly speaking, el martes usually means "on Tuesday" referring to this upcoming Tuesday. If the salon is closed every Tuesday as a general rule, Spanish speakers would normally say los martes (on Tuesdays). However, in everyday conversation, you will sometimes hear el martes used for a recurring weekly schedule too.