how do i firgure out how this couple is related

when i was looking up marriage records jose manueel villegas's sister gertrudis i found this page

https://familysearch.org/pal:/MM9.3.1/TH-1-18453-62919-41?cc=1874591&wc=12504491

the document says that she is related to her spouse, but it doesn't say how.

trying to figure this out will help me at least find the name of her grandparents on at least one side of her family.