I just want to charge a lithium battery, why does it have to be so complicated?
I ordered some 4,3V VMP 170mA solar panels (0.75 watt).
The BMS board say B+, P+ and R+, respectively the same for negative.
B= battery?
load "L" is which?
and "P" is power?
how to connect my 1S lithium board?

what do these letters stand for? "R"ollercoaster...? "P"atterycharger?
And "R" is?

 

You need a BMS made or sold by a company that knows about the BMS and tells you how to connect it in your language.

 

It has to be done properly so that You don't burn your house to the ground.
If You want easy, then buy a Cell that already has a BMS built-in.
.
.
.

 

I just want to charge a lithium battery, why does it have to be so complicated?
I ordered some 4,3V VMP 170mA solar panels (0.75 watt).
The BMS board say B+, P+ and R+, respectively the same for negative.
B= battery?
load "L" is which?
and "P" is power?
how to connect my 1S lithium board?

what do these letters stand for? "R"ollercoaster...? "P"atterycharger?
And "R" is?

Read the documentation that came with it. Much higher chance of finding your answer than hoping that strangers on the Internet are going to somehow how what some unspecified manufacture means by some labels on some unspecified product.

As for why it is a bit complicated, lithium ion batteries are notorious for exploding or bursting into flames if not treated properly. The battery management systems are what make these extremely finicky batteries even usable.

 

What’s bms

 

What’s bms

https://www.google.com/search?q=What's+bms

 

BMS= Battery Management System. If is functioning correctly it limits battery heating and prevents overcharging. If it is adequate it also switches off te charging when the voltage reaches full charge.