The lion is the national animal of England and is still prevalent in many areas of English society. The earliest use of the lion I can think of concerning England would be with Richard I’s nickname the ‘Lionheart’. If anyone has any further details on how England and the lion became almost synonymous I would be interested to know.
We get this question a lot here! There is a section of the FAQ about it, and u/jschooltiger also wrote about it: Why does England have a Lion on their flag, despite the fact there were no Lions in England?, with links to numerous other older answers.