What is wrong with my sentences in Spanish?

Vamos a el cine el lunes.
Yo compro videojuegos el lunes.
El jueves yo voy a el gimnasio.
El Domingo yo boy a la playa con mis amigos y comer a un restaruante delicioso.
My teacher put circles and letters over the sentences so I'm wondering what did I do wrong about them and how should I change them?
Thank you

Your teacher is the best source of that information.

Based on the sentences you provided, here are the corrections you need to make:

1. Vamos a el cine el lunes.
Correction: Remove the article "el" before "cine."
Revised sentence: Vamos al cine el lunes.

2. Yo compro videojuegos el lunes.
Correction: The sentence is grammatically correct.

3. El jueves yo voy a el gimnasio.
Correction: Remove the article "el" before "gimnasio."
Revised sentence: El jueves yo voy al gimnasio.

4. El Domingo yo boy a la playa con mis amigos y comer a un restaruante delicioso.
Corrections:
a) Change "Domingo" to "domingo" since days of the week are not capitalized in Spanish.
b) Replace "boy" with the correct verb "voy."
c) Add "a" before "comer" to indicate the purpose of going to the restaurant.
d) Replace "restaruante" with "restaurante" for correct spelling.

Revised sentence: El domingo yo voy a la playa con mis amigos y voy a comer en un restaurante delicioso.

Whenever you are unsure about your sentences, it's helpful to check grammar rules, use reliable online resources, or consult your teacher for guidance.