A Saudi Arabia employer sends a 'demand' to a licensed Nepali agency. You are selected, get a visa through your employer, and must get a Nepal labour permit before flying.
What you need
A job offer through a licensed Nepali agency
Passport valid 6+ months
Medical test at an approved centre
Nepal labour permit (Shram Swikriti)
Step by step
Only accept a job offered through a licensed recruitment agency (check it on dofe.gov.np) or a government (G2G) scheme.
Get the demand letter, contract and visa, and read the contract — salary, hours, food, housing, overtime.
Do the medical at an approved clinic and the 2-day pre-departure orientation.
Pay the welfare fund and insurance, and get your labour permit (Shram Swikriti) through FEIMS.
Keep copies of everything, including your receipt for every rupee paid.