Watchlist is a tool that allows you to "save" a particular asset to monitor it's activity without purchasing it! (Similar to adding something to your cart while shopping online without going through checkout).
For example, let's say you're viewing the details for stock XYZ. You're not quite ready to buy the stock, but you are interested to see what will happen to it's price over the next while. If you tap the eye icon in the top right corner this will add stock XYZ to your Watchlist.
To view your Watchlist, navigate to your dashboard and scroll to the bottom. All of the assets you've added to your Watchlist will appear in one place!
If you'd like to remove an asset from your Watchlist, tap the asset to go to the details page. If you tap the highlighted eye icon in the top right corner this will remove it from your Watchlist.