MRS VANDERTRAMP verbs

In French in the perfect tense most verbs take the verb avoir as the auxiliary verb (eg. They use part of avoir and the past participle). This could be used in a sentence like j’ai travaillé - I worked.
The Mrs Van Der Tramp verbs are exceptions and take être in the perfect. You can find the list online if you look it up. Mrs Van Der Tramp is a mnemonic to help remember them. These verbs also need their past participles to agree with the subject to you need to add an ‘e’ for feminine subject and an ‘s’ for plural ones. For example, je suis allé - I went (masculine subject) or je suis allée - I went (feminine subject).
I’d recommend the website languages online for some practice of forming and recognising the perfect tense - both of être and avoir verbs

Dr. Mrs. Vandertramp as a Mnemonic Device
Dr. Mrs. Vandertramp is a mnemonic device used to remember which verbs are conjugated with être as opposed to avoir in the passé composé. These are the verbs that are associated with the mnemonic:

Devenir (to become)
Revenir (to come back)

Monter (to go up)
Retourner (to return)
Sortir (to go out)

Venir (to come)
Aller (to go)
Naître (to be born)
Descendre (to go down)
Entrer (to enter)
Rentrer (to go home/to return)
Tomber (to fall)
Rester (to remain)
Arriver (to arrive)
Mourir (to die)
Partir (to leave)


https://www.fluentu.com/blog/french/dr-mrs-vandertramp-verbs/