The three words too, to and two sound exactly alike but have three distinct usages! They are classic examples of what we refer to as homophones—words that are pronounced the same but have different meanings and spellings.
As an adverb, too is used to describe something that’s “in addition, furthermore, moreover.” It’s another way of saying “also” or “as well” but usually fits more naturally at the end of a sentence. For example, “If you’re getting ice cream, I want some too!”
Another correct usage would be in describing “an excessive extent or degree; beyond what is desirable, fitting, or right.” So, you might be “too sick to travel” or “too tired to go for a run.”
As a preposition, to is used for “expressing motion or direction toward a point, person, place, or thing approached and reached (as opposed to from),” for example, “they came to the house.” Other uses include expressing direction or motion, a limit of movement or extension, expressing contact or continuity, and others. It can also be used as an adverb, as in “after he came to.”
This should be the easiest of the trio- two is a numerical value, so it’s used accordingly (“the number after one and before three is two“). The definition also includes the phrasing in two, for when you’re separating something into halves. “I split the log in two.”