For a Tier 2 (General) visa:
You must have :
-certificate of sponsorship reference number
-an ‘appropriate’ salary
-meet the English requirement
-900Pounds in savings
You don’t need to have 900Pounds in savings if A-rated sponsorer is certified claimed benefits to you
“A certificate of sponsorship is a reference number which holds information about the job and your personal details. It’s not an actual certificate or paper document.
Your sponsor will give you your certificate of sponsorship reference number.

Knowledge of English

You may need to prove your knowledge of the English language when you apply.
You can prove your knowledge of English by either:
-passing an approved English language test with at least CEFR level B1 in reading, writing, speaking and listening
-having an academic qualification that was taught in English and is recognised by UK NARIC as being equivalent to a UK bachelor’s degree

Documents you need to provide

-current passport/valid travel ID
-previous passports
-2 passport size colour photographs
-Passport photo requirements