This is the 1197th most frequent Turkish word.
yardımcısı
Assistant.
Here, 'yardımcım' refers to an assistant (a person who helps) in the context of a work environment.
Benim ofisteki yardımcım bugün izinli.
My assistant at the office is on leave today.
In this usage, 'yardımcısı' refers metaphorically to something that assists, in this case, a book helping with specific information or learning.
Kendime bir başucu kitabı yardımcısı buldum.
I've found a bedside book assistant for myself.
'Yardımcısı' here refers to a tool or equipment designed to assist with plant care.