Learn Spanish (Latin America): Debes evitar el estrés porque estás débil. - You must avoid stress because you are weak.

Debes is the 'you' form of deber, which we use to give advice or express an obligation. When you use deber to say what someone must do, the action verb that follows stays in its basic, unchanged form (the infinitive). That is why we use evitar (to avoid) right after it, rather than changing it to match the 'you' form.

Does debes mean 'you must' or 'you should' here?

It can mean either! Deber in the present tense translates to both 'must' and 'should' depending on how strong the advice is. Telling someone to avoid stress for their health works perfectly as either 'You must avoid stress' or 'You should avoid stress'.

Why is there an el before estrés? In English we just say 'avoid stress'.

In Spanish, when you talk about an abstract concept or a noun in a general sense (like stress, love, or life), you usually need to include the definite article (el, la, los, or las). Because of this rule, 'stress' requires the article and becomes el estrés.

Why use estás instead of eres for 'you are weak'?