When you don’t know something, it’s better that way.

For example,

If someone said a horrible rumor about you, and you didn’t know. It would be better that way so you can avoid a fight and trouble because someone said that about you.

You don’t have to worry about why he or she said that about you.

A common saying. Ignorance means unknowing or naive.

Bliss basically means a great thing in this saying.

So it means Not knowing is a great thing. Or you’re better off not knowing.

Example, when a child overhears a conversation meant for adult ears only and asks one adult out of curiosity, the adult may laugh and say “Ah…. ignorance is bliss.”

The “bliss” suggested in the phrase is only temporary.

For example, if the world were coming to an end and you didn’t know, you have no reason to be upset because you are ignorant that it is.

Example you think that your accountant has done some really creative accounting for tax evasion purposes only to find out at the end of the tax year that the Taxman was brighter and caught you out.