Please explain to me how a Type R instruction format works in $32-$bit instruction format.

I understand that the format for a type R instruction can be as follows:

ADD X$9,$ X$20,$ X$21$

where the $32-$bit instruction is as follows $10001011000101010000001010001001$

R $-11$bit opcode, $5$ bits $2$nd register, $6$ bits shift amount $(000000$ if no shift$),5$ bits $1$st register, $5$ bits register destination

But what do they mean by the $6$ bit shift amount? Give an example of $32-$bit instruction with a shift amount.