We use the uncountable noun equipment to mean ‘the set of things that you need for a particular purpose’, such as tools or clothing:
We’ve bought camping equipment, including new sleeping bags and a little refrigerator.
All of Vincent’s camera equipment was stolen from his car.
Because equipment is uncountable, we cannot say ‘an equipment’ or ‘equipments’. To refer to a single item of equipment, we say a piece of equipment:
On board is a piece of equipment – a radiometer called the ATSR – which can measure the temperature of the seas.