Difficult to see; hard to make out visually (because of darkness, small size, obstruction, etc.).
夜道は街灯が少なくて見えにくい。
The street at night is hard to see because there are few streetlights.
老眼で小さい字が見えにくい。
Because of presbyopia, small print is hard to see.
窓ガラスが曇っていて外がよく見えにくい。
The window is fogged, so it's hard to see outside clearly.
メガネをかけないと画面の字が見えにくい。
Without glasses, the text on the screen is hard to see.