"I am afraid of my wife."

Translation: Bojím se své manželky.

[Soolrak]

In another sentence, it says 'Bojíš se o tvoji manželku?' .... What difference does it make to use 'o' or not to use it? (In sense of meaning/translation of the word). Thank you in advance!

'Bojíš se o tvoji manželku?' = Accusative?
'Bojím se své manželky.' = Genitive?

[VladaFu]

That's correct.

"bát se o něco" vs. "bát se něčeho" vs. "bát se udělat něco"

"to be afraid for something" vs. "to be afraid of something" vs. "to be afraid to do something"

[claudio98_]

Can you explain why do we need to difference between genitive and accusative in this case?

[VladaFu]

See my comment above. o něco is accusative and něčeho is genitive. The meaning is different.

[Chessnecof]

Bojím se manželky is accepted as well. If I'm correct this could also mean to be afraid of wifes in general, in spoken Czech accusative. Right?

[VladaFu]

That is very unlikely. Plural manželek would be used.