This pattern is used to say that an action is hard to do, but the difficulty is usually subjective—it comes from your own feeling or situation, not from lack of skill or objective difficulty. For example, you might say この本は読みづらい if the font is small or the book is physically awkward to hold, not because you can't read well. It often carries a sense of discomfort or reluctance, like when something is emotionally hard to say or ask.

You form it by taking the ます-stem of a verb (the part before ます) and adding づらい. So 言う becomes 言い, then 言いづらい (hard to say). Similarly, 食べる -> 食べづらい (hard to eat, e.g., because it's too hot), 聞く -> 聞きづらい (hard to listen to, e.g., because it's embarrassing).

This pattern is used in everyday conversation and is neutral in formality, but it's more subjective than にくい, which indicates general difficulty. You'll often hear it with verbs like 言う, 聞く, 聞く, 頼む (to ask a favor), because those actions can be socially difficult.