uncle
The French word 'oncle' is used in the same way as the English word 'uncle'. It refers to a brother of one's father or mother, or to the husband of one's aunt. For example, 'Mon oncle habite à Paris' means 'My uncle lives in Paris'.
My uncle lives in Paris.
This sentence conveys a simple present tense action. In French, possession is often signified by using the word 'mon' before the noun, which corresponds to 'my' in English. 'Habite' is a present tense form of the verb 'habiter', which means 'to live' in English.
We have to visit my uncle tomorrow.
In this sentence, the phrase 'On doit' is equivalent to 'We have to' in English. It's followed by the infinitive form of a verb, in this case 'visiter', meaning 'to visit'. 'Demain' is the French word for 'tomorrow'.
Marie's uncle is a lawyer.
In the sentence, 'de' is equivalent to 'of' in English and is used to show possession. Note that the subject and verb are inverted compared to English – 'L'oncle de Marie' instead of 'Marie's uncle'. 'Est' is the third person singular of 'être', which means 'is' in English. 'Avocat' is a masculine noun referring to a lawyer.