In Russian, it is the case of a noun that shows what role the noun plays in a sentence. The table below shows how the noun Алексей (a male name) changes by cases.

First, you may see how important case endings are to show the role of a noun. Note, that the contrasting English equivalents have the name Alexey unchanged.

Second, it should be mentioned that the word order does not affect the meaning of a sentence significantly. For example, the sentence Анна ждёт Алексея has the same meaning as Алексея ждёт Анна as long as you use the accusative of Алексей.

Source masterrussian.com