Definition of bless verb from the Oxford Advanced Learner's Dictionary

bless

verb
bles
 
; bles
 
 
blessed, blessed
blest
 
; blest
 
1 bless somebody/something to ask God to protect somebody/somethingThey brought the children to Jesus and he blessed them.God bless you!2 bless something to make something holy by saying a prayer over itThe priest blessed the bread and wine.3 bless somebody/something (formal) to call God holy; to praise GodWe bless your holy name, O Lord.4 bless somebody/something (old-fashioned, informal) used to express surpriseBless my soul! Here comes Bill!‘Where's Joe?’ ‘I'm blessed if I know!’ (= I don't know)
Idioms

be blessed with something/somebody

to have something good such as ability, great happiness, etc
She's blessed with excellent health.We're blessed with five lovely grandchildren.

bless you

said to somebody after they have sneezed

bless you, her, him, etc.

(informal) used to show that you are pleased with somebody, especially because of something they have doneSarah, bless her, had made a cup of tea.
more at God bless at god