Basically, it means dont marry someone who isnt the same religion or who does not share the same religious beliefs. In other sections of the bible, it says the unbelieving spouse becomes a believer by proximity to the believing spouse(1 Corinthians 7:14 and (1 Peter 3:1–6).

What does unequally yoked mean in the Bible?

When oxen are unequally yoked, they cannot perform the task set before them. Instead of working together, they are at odds with one another.