You can find Conditions option in templates (not partial templates), headers, footers and popups. The Conditions define where exactly the template will be displayed.
How add/edit conditions?
to add or edit conditions click on options icon beside the title > Conditions
Conditions has two types (include and exclude). For example, we have an archive template and we will apply it to all posts archives except one archive.
What happens when multiple template use same conditions?
You must avoid this as much as you can. But if this happens the last template will be applied.