Take care
The word 'cuidar' in Spanish translates to 'take care' in English. It is often used in the context where one is told to look after or be cautious about something or someone such as in the case of caregiving or overseeing safety. For instance, you may 'cuidar a los niños' which means to take care of the kids. Furthermore, it could be used to express worry or concern toward a particular issue or situation.
You should take care of your health.
This sentence is giving advice about the importance of taking care of one's health. The verb 'cuidar' is in its infinitive form and is used here to mean 'to take care of'.
I will take care of the children tonight.
In this sentence, the speaker is indicating a future action that they will be performing, in this case taking care of the children. The verb 'cuidar' is used to mean 'to take care of' and it is followed by an object, 'a los niños' (the children).