In many poems the hidden meaning is the one most readers struggle with. Fortunately here, the poem "Shake" by Kelsea Osterman is very easy to interpret. The poem is very straightforward in meaning.
The narrator, I assume as being Osterman, is speaking to the reader about her experience with losing love. The love that she has lost is made more permeate with the loss of her own life. (Now, readers know that she does not actually commit suicide given the poem exists as a present tense voicing of her experience as she cuts the flesh of her wrist repeatedly.
Osterman speaks of the initial cut to her wrist forcing her body to shake. She watches as the blood drips to the floor as she takes the blade to her wrist again.
Metaphorically, the cutting of her wrist mirrors the pain that she experienced when she lost the love of the one whose words caused her enough pain to symbolically take her life (the life of her heart and love).
She wishes to kill the pain that she feels brought on by the words of her love; and by draining herself of blood she is also draining the pain that the loss of the love brought upon her.
Simplistically, the poem recalls the pain of a lost love and the actions one will take to rid themselves of the pain. Osterman could have left the poem as a suicide note, or as a reflection on how she was able to release the pain by causing pain to herself.
Regardless, the poem seems to mirror the work of the Confessional Poets given the poetry is all about personal experiences and typically dealt with themes such as death, depression, trauma, and personal relationships. These were new subject areas in literature (Confessional Poets emerged during the 1950s and 1960s) given that many times texts were not typically written from such an honest and open first-person point-of-view. In this type of poetry, authors dealt with very personal and sacrificial writings in which, basically, they "spilled their guts".
I was in a very depressed place when I wrote that poem. I had contemplated killing myself may times, after I wrote this poem I felt better. so I guess the summary of the poem is that I let someone hurt me and now I am better. I wanted to kill myself and so I in visioned what it would feel like if I did cut my wrist. How I would feel, I was also trying to include some sounds or other things into my poem.