Javier va a comer al restaurante porque tiene hambre.
Lena y yo vamos a descansar porque estamos muy cansadas.
Explanation:
When referring to to other people as in second person point of view it is best to use the words “va” for one person and “van” for multiple. “Va” and “van” both mean “going to.
When in first person point of view, it is best to use “vamos” or “voy”. “Vamos” to refer to “us” and “voy” to oneself.
Hope that helps! Have a nice day. ^^