Please check my sentences!!!!

I think bilingual should be defined as people being able to speak and understand two languages.
First, some says that people are bilingual when they speak two languages with native-like fluency. However, I think this definition is too strong, and few people do exist.
Second, being able to speak languages is absolutely necessary, but it is also important to understand the other person who speak language at native speed. Without understanding what a speaker says, you would not communicate with them in an appropriate manner.
In conclusion, I believe both speaking and understanding are crucial to be called a bilingual.