diff --git a/tidb-lightning/monitor-tidb-lightning.md b/tidb-lightning/monitor-tidb-lightning.md
index 01b9c6e823eb8..1e8a800455f7a 100644
--- a/tidb-lightning/monitor-tidb-lightning.md
+++ b/tidb-lightning/monitor-tidb-lightning.md
@@ -140,10 +140,10 @@ Metrics provided by `tidb-lightning` are listed under the namespace `lightning_*
     Counts idle workers. Labels:
 
     - **name**:
-        * `table`: the remainder of `table-concurrency`, normally 0 until the end of the process
-        * `index`: the remainder of `index-concurrency`, normally 0 until the end of the process
-        * `region`: the remainder of `region-concurrency`, normally 0 until the end of the process
-        * `io`: the remainder of `io-concurrency`, normally close to configured value (default 5), and close to 0 means the disk is too slow
+        * `table`: Number of unused `table-concurrency`, normally 0 until the end of process
+        * `index`: Number of unused `index-concurrency`, normally 0 until the end of process
+        * `region`: Number of unused `region-concurrency`, normally 0 until the end of process
+        * `io`: Number of unused `io-concurrency`, normally close to configured value (default 5), and close to 0 means the disk is too slow
         * `closed-engine`: number of engines which have been closed but not yet cleaned up, normally close to index + table-concurrency (default 8). A value close to 0 means TiDB Lightning is faster than TiKV Importer, which might cause TiDB Lightning to stall
 
 - **`lightning_kv_encoder`** (Counter)