"Wir haben sie gern."
Translation:We like her.
"gern" is an adverb and might be translated as "with pleasure". It expresses an enjoyment or happiness. So, doing something "gern" means "to like" doing so.
In this case you have "gern", or you like having. That is not a flowery phrase like: "It's a pleasure having you." but "to have" is taken a bit more strongly here. It is meant as "having in our lifes". So literally you could translate this sentence as: "We like that we have her in our lifes." Which is understood as "We like her (as a person)." So this is not a casual "gefällt uns" = "like her style" but rather close to "loving". Which I would personally see as another possible translation. Although there might be missing a "sehr" to make it really "loving". And it would be a friendly or family kind of love, not a lover's love.
I hope I could be of help.