You can open and pay into one each type of the different ISAs available per tax year.
For example, I can open EACH of the below accounts within a tax year and pay into them each concurrently (currently I have a H2B + LISA opened in the 19 - 20 tax year).
The types are:
Cash ISA - The Help to Buy (H2B) comes under this type
Lifetime Isa (LISA)
Stocks & Shares ISA (S&S)
This article provides a great summary beyond what I have shared here.