The first thing to know is that the center of this sentence is a similar comparison.
Then, omit the unimportant words and merge the words with similar meanings into:
A trainer is to 1980 what a master is to the early days.
In this way, you can understand:
In the early days, fencing and dancing masters were just like fitness instructors in the1980s.
In fact, the comparison object of this sentence is wrong. If your number 1980 is correct, it refers to people, but people cannot be compared with an earlier and later time.
Actually, parting is not that terrible. After 650,000 hours, when we are oxidized into wind, we can become two adjacent bubbles on the same glass of beer, a