It's possible we may need more details here. The site may have some sort of altered edit workflow in place that differs from Drupal's native behaviour which is similar to what you are used to.
Normally you can visit {website url}/admin/content in the backend, or visit a published page on the front end and click the "edit" link to edit content.
Cases where this isn't the case are pages on the site which are not "entity" in nature. (eg dynamically generated or code-generated pages/routes)
Unfortunately without knowing more about the site's setup it will be difficult to speculate. I would check for any modules that alter the edit workflow, or permissions structure. If a site uses something like Groups you may need to be a member of the group to alter that content.
It may also be possible that your user's role does not have sufficient permissions to edit content of that content type. In this case try editing the same content with the user/1 (First user on the site which has unalterable super administrative rights on the site, if you have access to it, or reach out to whomever has user modification abilities to alter your user role)
If your user has permission to edit permissions for users under { website url}/admin/people/permissions scroll down to (or ctrl+f) and find the permission that states
<your content type>: Edit any content
(and)
<your content type>: Edit own content
And make sure your user role has those options checked. Failing that ensure that your user role has the more permissive "Administer content" permission enabled. (this will override all other content edit permissions unless altered by another module)
You can try a couple of basic tests as well. If you know the node ID (numerical ID assigned to all nodes created) and manually construct the edit url to see if it's just something on the theme (admin/front end) that is hiding the edit buttons. The URL pattern used here is
website.tld/node/{THE NODE ID}/edit
Example:
website.tld/node/123/edit
You can check to see if the "Tabs" Block under {website url}/admin/structure/block is placed in a useable theme region and visible. This would allow you to edit the content from the front end if logged in as an appropriately privileged user.
On the back end admin area you can check the data view (under {website url}/admin/structure/views) the drives the {website url}/admin/content page to ensure that the "Content: Operations links (Operations)" field is placed in the view. Without that the edit/operations buttons will not appear in that view if you have permissions to view them.
This is just pure speculation, of course, not knowing how your website was constructed, or what custom code/contributed modules are being used.
Hope this helps.
