Assert new information or emphasize your point
よ at the end of a sentence tells the listener something new or emphasizes your point.
JLPTN5
Sentence + よ~ yo
you know; I'm telling you; [strong assertion]
Example Sentences

The train's here

Winter is cold
Add よ to the end of a sentence to assert information you think the listener doesn't yet know, a bit like "you know" or "I'm telling you." It adds emphasis and confidence to a statement. Use it sparingly, since overusing it can sound pushy. Compare it with ね, which instead seeks the listener's agreement.
Tips and Common Traps
Hana· Key point
Use よ when you're pointing something out that the other person might not have noticed, like telling a friend their train is about to leave or that a café is really good.