语言是音义结合的符号系统，是人类最重要的交际工具和思维工具。

语言是音义结合的符号系统，是人类最重要的交际工具和思维工具。

Language is a symbol system which combines sound and meaning together, and it's human beings' most important tool of communication and thinking.

combining sounds and meanings, language is a tool for human beings to communicate and think.

As a symbolic system combining sounds and meanings, language is the most important tool of communication and thinking of human beings.

As a semiotic system which combines sound and meaning, language is the most important communication and thinking tool.