Adverbial highly has 3 senses
  1. highly, extremely - to a high degree or extent; favorably or with much respect; "highly successful"; "He spoke highly of her"; "does not think highly of his writing"; "extremely interesting"
    Derived from adjective high1
  2. highly - at a high rate or wage; "highly paid workers"
  3. highly - in a high position or level or rank; "details known by only a few highly placed persons"
    Derived from adjective