suffix, i-adjective
likely to ...; have a tendency to ...
Attaches to the -masu stem of verbs to express that something tends to happen or is prone to happening. Often implies an undesirable or unintentional tendency.
彼は忘れっぽくて、約束を忘れやすい。
He is forgetful and tends to forget promises.
このガラスは割れやすい。
This glass breaks easily.
suffix, i-adjective
easy to ...
Attaches to the -masu stem of verbs to express that something is easy to do. Unlike sense 2, this sense focuses on the ease of performing the action, not a tendency.
このペンは書きやすい。
This pen is easy to write with.
この靴は歩きやすい。
These shoes are easy to walk in.