Total gains - This is the total gain/loss you have made on ALL your investments over your entire investment history. They can be segregated as below:
a) Realised gains - These are the gains or losses on investments (i.e. Mutual Fund units) that you have already sold either by redeeming, switching or during rebalancing (as that also involves redemption)
b) Unrealised gains - These are the gains or losses on investments (i.e. Mutual Fund units) that have not been sold yet and are a part of your current portfolio.
Note: Remember you can have losses too, so realized, unrealized or total gains can be negative as well.
To understand more terms that you may see on your dashboard, you can refer to our blog.