Many questions have been asked and answered by people with 0 knowledge so here's some light on the topic of travel Visas:

a thread from someone who applied for a dozen of them in 9 years in the Middle-east & EU, and having gotten 2 EU residency permits and renewed them 6 times. What are Visas?

Visas are travel permits issued by the "desired to be visited" nation's consulate.

They come with variables:

# of entries (how many times you can exit & enter the country)

Length of stay (days to months to years)

Purpose (Studies, work, meetings, tourism)