pyrcc5: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/pyrcc5 - from package: pyqt5-dev-tools

You may install the required package with command apt-get install {package}

Error in other languages:
pyrcc5: bevel nie gevind nie
pyrcc5: comandă negăsită
pyrcc5: comando não encontrado
pyrcc5: commande introuvable
pyrcc5: command not found
pyrcc5: käsku ei ole
pyrcc5: không tìm thấy lệnh
pyrcc5: komanda nerasta
pyrcc5: Kommando nicht gefunden.
pyrcc5: kommandot finns inte
pyrcc5: komut yok
pyrcc5: nie znaleziono polecenia
pyrcc5: níor aimsíodh an t-ordú
pyrcc5: no se encontró la orden
pyrcc5: no s'ha trobat l'ordre
pyrcc5: opdracht niet gevonden
pyrcc5: parancs nem található
pyrcc5: perintah tidak ditemukan
pyrcc5: príkaz nenájdený
pyrcc5: příkaz nenalezen
pyrcc5: команда не найдена
pyrcc5: командата не е открита
pyrcc5: 命令找不到
pyrcc5: コマンドが見つかりません