I'd like to have quicker access between two folders,
so, how can I create a link from a folder to another one, please?

EDIT:
I found it.
In Terminology, I had to do

Isn't there a way without typing the sometimes very long paths, i.e. without using the terminal?

You can shorten things a bit:
1) Create the link while sitting in the directory where you want "/path of where to put link" so you only have to type the name. e.g.
RATHER THAN:
ln -s /this/dir/is/very/long/dont/you/think /this/otherdir/is/also/very/long/to/type
INSTEAD:
cd /this/otherdir/is/also/very/long/to
ln -s /this/dir/is/very/long/dont/you/think type

Any later references to "/this/otherdir/is/also/very/long/to/type" will work just as they would if you'd done the first syntax.

2) If the directories have a common path you can use relative links e.g.:
RATHER THAN:
ln -s /this/dir/is/very/long/dont/you/think /this/dir/is/very/long/dont/we/know
INSTEAD:
cd /this/dir/is/very/long/dont/we
ln -s ../../you/think know

The ../../ makes it relative to the common /this/dir/is/very/long/dont subdirectory of both the target and the link.

Isn't there a way, when right clicking a folder, to create a context option like "Create a link to that folder"?
Then you could move that link to wherever you need it.

Would be quite a handy thing, I guess.

There probably is but I don't spend a lot of time in GUIs myself. The real power comes at command line.

These days even MS Windows servers don't install the GUI by default and they recommend using command line (Powershell).

You can create a symlink with a particular SW. From time to time I use Double Commander and under Files menu item you can find creating a symbolic link.

Yes, you can do it in pcmanfm.

Find the folder you want linked somewhere else. Highlight it. From the pull down menu select edit/Create Link. Then select the folder you want to put the link.

Wow, a-ma-zing!!!
Didn't know it was that easy!
Much better than the uncomfortable way with the terminal.

Thank you very much!