AlphaExplorer is the generic name of an ad-supported application for Mac.
AlphaExplorer belongs to the large family of AdLoad adware variants and clones. You may see its icon in the Applications folder - a circle with a magnifying glass icon in it - the same icon as the one used by hundreds of other AdLoad variants, all made to look purposefully generic to help them stay hidden among your other apps.
AlphaExplorer has a singular purpose - to deliver ads to your browser of choice. The problem here is not so much the ads themselves. The real issue is that adware of this kind may work together with rogue ad networks and deliver ads through them. This means that the ads delivered to your browser may be sourced through those rogue ad networks.
This type of ad may refer to untrustworthy or malicious pages, scam or phishing websites, potentially unwanted application installers, or misleading websites.
This should make it clear why you don't want to have adware on your Mac, no matter if it is AlphaExplorer or any other adware package.
Removing Mac adware is usually easy and boils down to dropping the adware's icon from your Applications folder onto your Trash.