An analytic language is a language that organizes words and grammar by a strict word order instead of inflections, or word endings that show grammar. Examples of analytic languages include Chinese, English, Vietnamese, Thai, Khmer, and Lao.
In Chinese, sentences are mostly in the SVO (subject-verb-object) word order. So the sentence must be "I eat noodles", not "I noodles eat" or "eat I noodles". In Chinese this is written as 我吃面条. The verb 吃 (pronounced chī, meaning: "eat") does not change based on the subject "I" or the object "noodles", and likewise the subject 我 (pronounced wǒ, meaning: "I") and object 面条 (pronounced miàntiáo, meaning: "noodle/noodles") do not have any special word endings based on its role or number. What is important is that all the words are in the correct order.
Modern English does have some inflections based on the subject (the verb "eat" becomes "eats" when the subject is a third person "he/she/it") and number ("noodle" is singular while "noodles" is plural), but aside from that, there are almost none. Therefore, Modern English is mostly an analytic language. Modern English has far fewer inflections that almost all other Indo-European languages, such as Spanish, German, and Russian.
Old English was an inflectional language and content words could have several different word endings, much like German today. However, England was taken over by speakers of other languages, especially French, Danish, and Latin, and since the new rulers became second language speakers of English, the grammar simplified to what it is today.