In urethral stricture What is urethral dilation, urethrotomy and urethroplasty and what are the advantages and disadvantages of each one?

It depends... Dilation is simply stretching the area of the stricture. The others involve somewhat more extensive surgery. The best option varies widely from one case to another; none is always better or worse. The best option often cannot be determined until the procedure is underway. Your urologist can best explain all this.