This is your unique AdSense Publisher Id given by Google. You can see your Adsense id on the top right corner of Google Adsense Panel. It is a number starting with “pub-“. For this field, you need to enter “pub-” in front of your id.
The title is shown before the widget content. Its display is depending on your theme.
Adsense widget supports all the ad types provided by Google Adsense. (See : Available ad formats)
Slot id defines AdSense visual elements of your ad unit. After you create a new AdSense unit with the current Google Adsense generator, it is embedded inside the code.
Slot id stores color, size, font & corners options. If you specify a slot id for the ad you have added, it will get all those settings from the ad you created.
One great advantage of using slot id is that, if you change the colors from Manage Ads panel in Google Adsense control panel, color scheme will be updated on all ad units using same slot id.
Channel id allows you to track reports of your AdSense units. Every channel displayed separately on Adsense reports. You can see your top channels on Reports Overview.
It is good practice to use definitive channel names like ShailanComSidebar OR ShailanComTopBanner.