Hi,
There are 4 different types of ISAs, cash ISA, stocks and shares ISA, innovative finance ISA and the lifetime ISA. You were always able to open up to one of each in a tax year, except for a lifetime ISA, so you could for example, open a cash ISA and a lifetime ISA in the same tax year. You can see guidance here:
Individual Savings Accounts (ISAs)
A new UK ISA with its own allowance of £5000 came into effect from 6 April 2024. This is separate from the £20000 existing allowance.
Thank you.