Well, if you knew anything about PR then you'd be more knowledgeable and you'd be able to understand.
Let me explain, but I guess I'm going to have to do this quite simply, so I'll use the German federal elections because they use FPTP and PR on the same day at the same time.
en.wikipedia.org
This is the 2017 election.
The CDU/CSU got 37.27% of the vote with FPTP. They got 231 seats out of 299 seats available. Which is 77.25% of the seats.
The SPD got 24.64% of the votes and 59 seats, or 19.7%.
The AfD got 12.64% of the vote and 3 seats, or 1%
The FDP got 7% and zero seats, or 0%
The Left got 8.55% of the vote and 5 seats, 1.64%
The Greens got 8.01% of the vote and 1 seat, or 0.33%
So, The CDU/CSU got nearly three times the number of seats they should have had.
The SPD got 5% less, the AFD got 11% less, the FDP got nothing, even though 7% of the country gave them votes. The Left and the Greens also lost out.
With PR it was totally different.
The CDU/CSU got 32.93% of the vote. They lost more than 4% of the vote. Meaning that on the same day, at the same time with the same voters, 4% of people, meaning about 203,000 people, decided to change their vote.
FPTP forced them to vote for a larger party, when really they wanted to vote for someone else.
The CDU/CSU ended up with 246 seats out of 709. That's 34.7% of the seats.
The other parties all did better because the electoral system says that whatever your vote is, your seat allocation is going to be similar to that.
With FPTP a third party vote is wasted because only the two main parties are going to have a say most of the time.
With PR it's totally different.
The FDP, a total waste of a vote with FPTP, got 10.75% of the vote, up from 7%, so clearly 3.75% of the electorate thought it wasn't a wasted vote with PR when it was with FPTP, and they got 80 seats.
After the results came in Angela Merkel tried to form a "Jamaica coalition", which is CDU/CSU, FDP and Greens, it didn't work out, so it went for a "grand coalition" of the CDU/CSU.
However you still get represented in parliament, government has to be more conscious of the people.
The biggest difference is that in 2015 in the UK (with FPTP) UKIP got 12.6% of the vote and one seat, the AfD in 2017 in Germany (with PR) got 12.6% of the vote and 94 seats.
So, the CDU/CSU were punished and had to change their attitude.
In the UK the Tories didn't feel that much heat, except that in some seats they lost MPs (but still won the election).
PR allows people to punish. FPTP doesn't.