How to print the variable name along with its value?

In simple way:

j="jjj"
k="kkk"
l="lll"

for i in {j,k,l}; do echo "$i = ${!i}"; done

The output:

j = jjj
k = kkk
l = lll

---

• ${!i} - bash variable expansion/indirection (gets the value of the variable name held by $i)

If you have bash v4.4 or later you can use ${VAR@A} Parameter expansion operator.

This is discussed in the Bash manual under section 3.5.3 Shell Parameter Expansion

'A' Operator

The expansion is a string in the form of an assignment statement or declare command that, if evaluated, will recreate parameter with its attributes and value.

So with this you can do:

j="jjj"
k="kkk"
l="lll"

for i in {$j,$k,$l}; do 
    echo "${i@A}"
done

And your result should be:

j='jjj'
k='kkk'
l='lll'

Or in zsh use declare -p

% j=jjj; k=kkk; l=(l l l)               
% for v in j k l; do declare -p $v; done
typeset j=jjj
typeset k=kkk
typeset -a l=( l l l )
%