to be and to have in French

Les verbes être et avoir en français

The verbs être (to be) and avoir (to have) are essential verbs you need to memorize.
They are both irregular. Let’s start with être:
je suis - I am 
nous sommes - we are
tu es - you are (familiar) 
vous êtes - you are
il/elle est - he/she is 
ils/elles sont - they are
Note that the -s of vous is pronounced as a z when followed by the vowel ê in êtes.
Elle est américaine. - She is American.
Vous êtes brésilien? - Are you Brazilian?

The verb avoir (to have)
The verb avoir (to have) also has an irregular conjugation.
j’ai - I have 
nous avons - we have
tu as - you have 
vous avez - you have
il/elle a - he/she has 
ils/elles ont - they have

Note that the -s of nous, vous, ils, elles is pronounced z when followed by a vowel.
Ils ont une belle maison. - Th ey have a beautiful house.
Vous avez un instant? - Do you have a moment?

Note that un, une, and des change to de or d’ when the verb is in the negative form.
Tu as des amis à Paris? - Do you have friends in Paris?
Non, je n’ai pas d’amis à Paris. - No, I do not have friends in Paris.
Il a des enfants? - Does he have (any) children?
Non, il n’a pas d’enfants. - No, he does not have (any) children.
The verb avoir is used in many common idiomatic expressions. 

Here are a few examples:
j’ai de la chance - I am lucky
j’ai besoin de… - I need . . .
j’ai chaud - I am hot, warm
j’ai envie de… - I feel like . . .
j’ai faim - I am hungry
j’ai froid - I am cold
j’ai honte - I am ashamed
j’ai l’air de… - I seem, I look . . .
j’ai mal - I have a pain, it hurts
j’ai peur - I am afraid
j’ai (trente-cinq) ans - I am (thirty-fi ve) years old
j’ai raison - I am right
j’ai soif - I am thirsty
j’ai tort - I am wrong

When referring to the state of one’s body, French uses avoir mal à (having an ache or pain).
J’ai mal à la tête. I have a headache.
Il a mal au bras. His arm hurts.

When avoir mal à is followed by a verb, it means to have trouble doing something.
Nous avons du mal à accepter sa décision. We have trouble accepting his decision.
Elle a du mal à monter l’escalier. She has trouble climbing the stairs.