Your details will be uploaded to the UK Visas and Immigration (UKVI) database and you will receive a Confirmation of Acceptance for Studies (CAS) which includes a reference number. You will need this number to apply for your visa.
The CAS will be sent to you after you have fulfilled the conditions of your offer and paid the required deposit towards your tuition fees.
The CAS will include details about your course - level, duration and fees. Your visa application will be considered based on these details.
Your visa will be tied to the study the specific course at the institution that issued you the CAS.