The phrase "Get Over It" means to accept something that happened in the past and move on.
Example of use: Danny—"I'm really bummed that I lost the game last night" Rosa— "You need to get over it and focus on winning today's game."
When we talk about “getting over it,” we’re discussing finishing something – be that an illness, an emotional upset, or something else entirely. The origin of the idiom “get over it” is attested to use of the word “over” as a late 14th century meaning for “recover from.” The term is first seen in literature in John Behervaise’s Thirty-six Years of Seafaring Life published in 1839, referencing an amputation: “Such was his state that no one supposed he could ever get over it.”