Translation:My grandfather and my grandmother love each other.
-Ha' has several uses, and sometimes it's a bit idiomatic what the result of combining it with a particular word will be.
In general, the meaning is to do something wrongly (e.g. jatlh "speak", jatlhHa' "misspeak", i.e. say the wrong thing) or to undo something (e.g. nob "give", nobHa' "give back, return").
Sometimes, the meaning is close to the opposite (e.g. pol "keep", polHa' "discard") -- this seems to me to be particularly common with adverbs (e.g. nIteb "alone", nItebHa' "together").
-Ha' can be a bit unpredictable, and the safest thing might be to learn words with -Ha' as "separate words".
For parHa' and muSHa', translations as "like" and "love", respectively, are relatively common, even if it might be debatable whether it's possible to "mis-dislike" or "un-dislike" someone or something, i.e. whether something like parHa' even has a meaning. But assigning it a meaning of "like" is fairly conventional among Terran speakers. (And similarly for muSHa'.)