Where can i ckeck all the attribute fields of salesforce objects?

All fields are listed in the SOAP Api documentation. Here's the one related to the Opportunity sObject: https://developer.salesforce.com/docs/atlas.en-us.218.0.api.meta/api/sforce_api_objects_opportunity.htm.

Each operation available on the field is noted in "Properties".

In your case, you can see that the IsClosed and IsWon fields can't be updated because the operations listed are: Defaulted on create, Filter, Group, Sort

Finally, You can also check the other objects thanks to the navigation menu on the left.