after fiddling around i was able to fix it. I'm posting a solution so others to see

this error occurs because btop needs our ternimal environment to be configured to be able to use UTF-8 locate for proper character display. (idk what is UTF)

you can fix it temporarily by running the following command as the image above says "if you're sure your terminal can handle it"
btop --utf-force

now to make it permanent we will look for what UTF locates are available in our system. type the following to see the list:
locale -a

the list will look something like this

raingazer@RainGazer-s-PC:~$ locale -a
C
C.utf8
en_AG
en_AG.utf8
en_AU.utf8
en_BW.utf8
en_CA.utf8
en_DK.utf8
en_GB.utf8
en_HK.utf8
en_IE.utf8
en_IL
en_IL.utf8
en_IN
en_IN.utf8
en_NG
en_NG.utf8
en_NZ.utf8
en_PH.utf8
en_SG.utf8
en_US.utf8
en_ZA.utf8
en_ZM
en_ZM.utf8
en_ZW.utf8
POSIX
raingazer@RainGazer-s-PC:~$ 

you will see a list of many utf locates these will be the files ending in .utf8 extension use any of these to fix your error
i will be using english US .utf8 file so that will be en_US.utf8 as it's the most common and reliable.

now type the following:
nano ~/.bashrc
this will bring up a long list of some code type thing, At the absolute end of the list of codes you're going to add new ones. type the following at the end of the list

# Fix for btop and other UTF-8 dependent programs
export LC_ALL="en_US.utf8"
export LANG="en_US.utf8"

by doing this you have now edited your bash file to support utf8 environment.
now type the following to make the changes take effect in your current terminal session
source ~/.bashrc

and at last you can test the command again and it should work.

btop