How decription is done at server side when server receives request from encripted link from browser

what is happing at browser side and server side ?

help me to know this.

Suppose below is link :

https://example.com/main?ajcbeu456ds2decrr=rgfdrgfgref

Now ‘ajcbeu456ds2decrr=rgfdrgfgref’ this part is encripted how server knows data behide this encription to give the response ?

while key is not shared with any where or not stored in specific file.

help me to know this.