I want to know what is the advantage of time series database if we compared to traditional database
The short answer is that a time series database is more specialized and better able to handle the unique problems of time series data. InfluxDB, for example, is optimized for higher writes so that data can be sent in high volumes.
You can read a longer explanation here.
can you tell me the problem of traditional data base
It really depends on your data, the volume, the frequency of writes and reads, etc. It’s possible to configure and optimize databases to work for all sorts of problems they weren’t built for, but using a specialized database is more about making it easier for you to store and retrieve data with less configuration.