"有靠背的长椅" can be translated into English as "a bench with a backrest" or "a long bench with a back".
"Bench" refers to a long seat for multiple people, often found in parks or other public spaces.
"With a backrest" or "with a back" clarifies that the bench has a supportive structure at the back for sitting comfortably.
Both expressions are commonly used and convey the intended meaning accurately.