Does anyone know any free keyword tool i can use to get the number of people that searched for a particular keyword in a month at google?
You can use the Google AdWords keyword tool for approximate search volume on Google + their search network. You might also want to check out these free keyword research tools for more help.
I use Google Adwords Keyword Tool because this tool provides information like overall search volume for a keyword, last month search volume, advertisers competition, highest volume of search occurred, estimated average CPC, estimated ad position, search volume trends.