This is the 17222nd most frequent Russian word.
строителями
"Builders" or "construction workers" (instrumental plural form).
In this sentence, "строителями" is used in instrumental case plural form to denote the people with whom the conversation is taking place, specifically the builders.
Мы говорили со строителями о проекте нового дома.
We spoke with the builders about the new house project.
Here, "строителями" again is in instrumental case plural, indicating the role or position the individuals hold in their profession.
Они работают строителями уже много лет.
They have been working as builders for many years.
In this context, "строителями" is used in instrumental case plural to depict cooperation or partnership with the builders during the renovation process.