Within the SkillData for your custom skill, there are the data fields "DisplayName" and "Description" (ignore the DisplayNameRef and Description Ref). Put whatever you want into these fields (for this example, I'll use "CowSkill" for DisplayName and "FlyingCow" for Description).
When the game sees those fields for the skill, it looks in the Localization folder/TranslatedStringKeys to see what should be displayed. In the Editor, in the top middle, you can see a "TranslatedStringKeys" button. If you open that up and create a new file there, a spread-sheet-like field pops up. The two most important columns are "Key" and "Content" (or whatever is right next to Key).
Put the DisplayName and Description names you put in the SkillData into the Key fields. Right next to them you can then type out the actual in-game skill name/description.
Key | Content
CowSkill | Summon the Flying Cow
FlyingCow | Who needs flying pigs when there are flying cows?
