The numbers in an AbsDimension inside an Offset inside an Anchor are just like the values you pass to SetPoint in Lua. The Lua equivalent of that XML would be:
Code:
<parent frame reference>:CreateFontString("PlayerLevelText", <draw layer>, "GameFontNormalSmall")
PlayerLevelText:SetPoint("CENTER", -63, -16)
From there it's hopefully obvious what to do.