User-friendliness is the noun for the quality of being user-friendly — how easy a thing is for an ordinary person to use, understand and operate without training or a thick manual. You use it when judging designs: "the user-friendliness of the new app", "they improved user-friendliness by making the buttons bigger".

User-friendliness is the noun for the quality of being user-friendlyUser-friendliness是user-friendly這個形容詞的名詞形式 how easy a thing is for an ordinary person to use, understand and operate指的是一般人使用、理解、操作一個東西有多容易 without training or a thick manual不需要訓練，也不需要一本厚厚的說明書 You use it when judging designs評斷設計時會用到它 'the user-friendliness of the new app'像'the user-friendliness of the new app'（這款新App的易用性） 'they improved user-friendliness by making the buttons bigger'或'they improved user-friendliness by making the buttons bigger'（他們把按鈕做大來提升易用性）

It is mostly said about machines, software, websites and apps, but it stretches to anything with instructions or controls — a ticket machine, a rice cooker, a form you must fill in. It is uncountable: no plural, no "a".

It is mostly said about machines, software, websites and apps它大多用在講機器、軟體、網站和App but it stretches to anything with instructions or controls但也可以用在任何有說明或操作介面的東西上 a ticket machine, a rice cooker, a form you must fill in像售票機、電鍋，或你必須填寫的表格 It is uncountable它是不可數名詞 no plural, no 'a'沒有複數，也不能加'a'

It has a slightly official, report-and-review feel; a friend chatting would just say "it's easy to use". Note the meaning is about the person using it, not about how the thing looks.

It has a slightly official, report-and-review feel它帶點正式、像報告或評論的感覺 a friend chatting would just say 'it's easy to use'朋友聊天時只會說'it's easy to use'（這個很好用） Note要注意 the meaning is about the person using it這個字的意思是關於使用它的人 not about how the thing looks而不是這個東西看起來怎麼樣

Something can be beautiful and still have terrible user-friendliness. In the workplace people often use the word "usability" for the same idea.

Something can be beautiful一個東西可以很美 and still have terrible user-friendliness但user-friendliness卻很差 In the workplace在職場上 people often use the word 'usability' for the same idea大家常用'usability'這個字來表達同樣的概念