European texts of Middle ages had no spaces as well andpeoplewereabletoreadthetextsbecausetheyknewthewords so, this is how Chinese, Japanese and other no-spaces-language people read prior knowledge is the key point here however if Chinese people will add spaces -- they will have more success in making Chinese the international language because Chinese is as easy as English x-tremely simple grammar 如果 汉语 词 之间 有 空， 读 句 更方便。

For this question, you can try to understand it by using GRAMMAR. Just as English, there are SUBJECT, PREDICATIVE in one sentence. This is my FRIEND. 这 是 我的 朋友. "This" and ‘这" are subjects in the sentence. “is”and“是" are copulative verbs. ”Friend“and"朋友"are nouns, are PREDICATIVE. So, when you know the nouns in one sentence, then they often are compound words, you should read them as a noun. Help you can understand it.

朋友 itself is a word, you don't need to read ”朋友" separately^^ Here are some examples 我们 是 朋友 这 是 我 姐姐 它 是 我 的 宠物。 It would be better to look up the dictionary to find whether the word is a compound word or not^^ Best wishes

Quite interesting point you are making there, the short answer is to expand your vocabulary, so that your brain is able to pick up these hidden compound words automatically in the future. Also the context is very important.

We have lots of form to separate words. You can also say 这是 我 朋友 You can also think about it using the English words. For this case, This is my friend. friend is not a separate word, so you can let it as a compound word. As general, when you learn a vocab, most of them they compound words. Hope it can help u.