This is not explicitly covered
By RAW, on a successful wisdomWisdom or intelligenceIntelligence check, there's nothing that indicates the Ranger gets more info than any other class. The favored enemyFavored Enemy rulefeature description states:
You have advantage on Wisdom (Survival) checks to track your favored enemies, as well as on Intelligence checks to recall information about them.
What you get is easier access to the info by virtue of gaining advantage on intelligence checks.
However the description of favored enemyFavored Enemy also states:
Beginning at 1st level, you have significant experience studying, tracking, hunting, and even talking to a certain type of enemy.
While this is flavor text, it does suggest that the ranger has considerable knowledge, moreso than other players, of their favored enemy.
I've approached this in several different ways as a GM:
Ask the player
Sometimes I simply ask the player what information they want to recall and then they roll to recall it. This can be any info they choose about the enemy from its stats or description. If they fail the roll they can't try to recall that same info until the next day. However they can try to recall different info on the same day.
Sometimes I just choose as GM which info to give. When I do this I give 3 pieces of basic info, like creature name, AC, and HP (+/-20%) and then an additional number of pieces of information equal to intInt mod + profproficiency bonus. For example a 1st level-level ranger with 12 int would get 1 + 2 additional bits of info of my choosing. I try to keep at least some of the info useful in the moment, but might also include quirky bits of info.
Consistency and fairness
It feels to me most fair to the players if the GM chooses a method and sticks with it for the entire campaign. Also, I like to have some part of the mechanic encourage me as GM to give more info than I normally would, otherwise there doesn't seem to be any benefit to the favored enemy feature.