The aunts and uncles
In French, 'Les tantes et les oncles' refers to 'The aunts and uncles'. It's commonly used in the context where you would talk about your extended family in English. Notice that les is repeated before both nouns in the phrase, which is a standard practice in French when referring to more than one type of thing or person in a list.
Pierre's aunts and uncles are very kind.
This sentence describes the kindness of Pierre's aunts and uncles, using 'Les tantes et les oncles' to refer to these family members.
I met Marie's aunts and uncles yesterday.
This sentence is about the speaker's encounter with Marie's aunts and uncles, signified by 'Les tantes et les oncles', the previous day.
Paul's aunts and uncles live in France.
This sentence tells us about the place of residence of Paul's aunts and uncles, referred to as 'Les tantes et les oncles', which is France in this context.