This is the 8487th most frequent Japanese word.
手書き
Handwriting; handwritten.
Here, '手書き' (tegaki) is used as a noun indicating that the method of writing the letter was done by hand, as opposed to typed or printed.
この手紙は手書きで書かれています。
This letter is written by hand.
In this sentence, '手書きの' (tegaki no) modifies 'メモ' (memo) to describe a note that is handwritten.
私は手書きのメモをよく取ります。
I often take handwritten notes.
The use of '手書きで' (tegaki de) specifies that the action of filling out the forms should be performed using handwriting.