Here's a breakdown:
* Rwy'n: This is the first person singular present tense form of the verb "to be". It means "I am".
* dy: This is the second person singular possessive pronoun. It means "your".
* caru: This is the verb "to love".
* di: This is the second person singular direct object pronoun. It means "you".
So, the full sentence translates to "I am loving you", which is a common way to express "love you" in Welsh.
You can also say "Cariad" which simply means "love". It's a shorter and more informal way to express affection.