Bandwidth is a term that defines how quickly you are able to move a certain amount of data online. The larger the bandwidth, the more data you are able to move fast.
What This Means For You
This is less about how many employees you have and more about what information you deal in. If you transfer large image and video files you will want to go for as much as your budget allows. If you only deal in emails or small text files then you can get away with less bandwidth without this having an adverse effect on your network.
If you are unsure of your company internet speed, head over to SpeedTest. If you are only getting 9-10Mbps and you are transferring files, you may need to upgrade your package.
There are several other speed test sites compatible with different browsers. The above link is perfect for Internet Explorer and Google Chrome.