This phrase literally translates as 'brake on the iron' but it is actually a slang term used to refer to a sudden stop or change. It is used to describe a situation where someone or something comes to an abrupt halt, or a rapid change of plans.
Examples
- Spanish: Iba a salir con mis amigos, pero tuve que frenar en el hierro cuando mi jefe me pidió que trabajara horas extras.
- English: I was going to go out with my friends, but I had to put the brakes on when my boss asked me to work overtime.