To zero in on a target means to aim at it or move towards it. If you zero in on a problem or subject, you give it your full attention. Also, to adjust the gunfire so as to be aiming directly at a target. To concentrate attention on, or to focus on.

For example:

Can you have the camera zero in on that tree?

Many of the other major daily newspapers have not really zeroed in on the problem. 

He raised the binoculars again and zeroed in on an eleventh-floor room. 

Critics have zeroed in on his plan to raise gasoline taxes 10 cents a gallon.

The drones zeroed in on the rebels’ positions.

We must decide on our target market and zero in on it.

It has taken multiple drafts, but I think I’m finally zeroing in on the right tone for my novel.

Tradução:

O idiom “zero in on” sugere que se ajuste o foco para se concentrar em um único alvo, seja ele um problema, uma pessoa ou uma ideia. É uma expressão informal que pode ser usada tanto em contextos profissionais quanto pessoais.

“Focar”, “apontar ou visar”, “identificar”, “convergir” ou “concentrar-se em torno de” uma questão qualquer.

Exemplos:

“The auditor knows how to zero in on the problems.” – “O auditor sabe focar nos problemas.”

“The newspapers have zeroed in on his private life.” – “Os jornais focaram na vida particular dele.”