Questions & Answers about Мастер сказал, что плинтус у двери нужно починить.
Not usually. In this kind of everyday sentence, мастер usually means something like repairman, technician, worker, or handyman, depending on context.
So Мастер сказал... is more like:
The repairman said...
rather than The master said...
Russian мастер can mean a skilled specialist in many contexts, so the exact English word depends on the situation.
Because что introduces a subordinate clause.
The sentence breaks into two parts:
- Мастер сказал = The repairman said
- что плинтус у двери нужно починить = that the baseboard by the door needs to be repaired
In Russian, subordinate clauses are normally separated by a comma, so the comma before что is required.
Because Russian past tense agrees with the subject in gender and number.
Here the subject is мастер, which is masculine singular, so the verb is сказал.
Compare:
- мастер сказал = the male worker said
- мастерица сказала = the craftswoman said
- мастера сказали = the workers said