It could be anything, you haven't given anywhere near enough information to be able to help.

Is it happening when the car is stood still and engine running? Or when driving? If so at what speed? When driven over bumps? A rotational noise in time with the wheel speed? During braking?

The more info you give the easier it will be for someone to help, but

"The sound is coming from rear left.

It's like metallic sound and you can hear it more when car is warmed up".

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.

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could be absolutely anything.
