Meaning: People who construct buildings do difficult jobs for the whole day.
Choice of Words: Builders are people who build things. Work means to do a job or task. Hard means difficult or needing a lot of effort. All day means the entire day.
Alternative Expressions
The builders are working hard all day.
Meaning: This sentence is telling us that the specific people who are building something are currently working very hard for the whole day.
Choice of Words:The builders are the specific people who are building something. Are working means that they are currently doing work. Hard means they are putting in a lot of effort, and all day means for the entire day.
It's hard work for the builders all day long.
Meaning: This sentence is telling us that the work that the builders are doing is very hard and they are doing it for the whole day.
Choice of Words:It's is a contraction of the words "it is," which means something exists or is true. Hard work means work that requires a lot of effort. For means something is intended for or belongs to someone. The builders are the specific people who are building something. All day long means for the entire day.