“Literally Tawheed means “unification” (making something one) or “asserting oneness,” and it comes from Arabic verb wahhada which itself means to unite, unify, or consolidate. However, when the term Tawheed is used in reference to Allah (i.e., Tawheedullah), it means realizing and maintaining of Allah’s unity in all of man’s actions which directly or indirectly relate to Him.”

Could you kindly explain the part "realizing and maintaining of Allah’s unity in all of man’s actions which directly or indirectly relate to Him."?

It means maintaining tawheed and not committing shirk in our actions. In our acts related to Allah tawheed should be maintained.