The Feed Tab is smack dab in the middle of your channel, so you want to keep it full of new activity. This doesn't necessarily mean that you have to be uploading new videos all the time. Commenting, liking, sharing and subscribing also show up in your feed, and are an easy way to provide interesting content to people visiting your channel and get more YouTube subscribers.
This is also where you can enable or disable channel comments. It's generally nice to have open communication and allow channel comments automatically, but if you have problems with spammers - which can happen a lot on YouTube - you can disable comments or allow them only after approval.
