diff --git a/python/pyspark/sql/dataframe.py b/python/pyspark/sql/dataframe.py
index 9f86086dad83d..43dd30b8ca8ee 100644
--- a/python/pyspark/sql/dataframe.py
+++ b/python/pyspark/sql/dataframe.py
@@ -305,11 +305,12 @@ def explain(self, extended=None, mode=None):
         is_mode_case = mode is not None and isinstance(mode, basestring)
 
         if not is_no_argument and not (is_extended_case or is_mode_case):
-            argtypes = [
-                str(type(arg)) for arg in [extended, mode] if arg is not None]
-            raise TypeError(
-                "extended (optional) and mode (optional) should be a bool and str; "
-                "however, got [%s]." % ", ".join(argtypes))
+            if extended is not None:
+                errMsg = "extended (optional) should be provided as bool" \
+                    ", got {0}".format(type(extended))
+            else:  # For mode case
+                errMsg = "mode (optional) should be provided as str, got {0}".format(type(mode))
+            raise TypeError(errMsg)
 
         # Sets an explain mode depending on a given argument
         if is_no_argument:
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala b/sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala
index 42338bd8accac..3fb82420a515c 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala
@@ -547,6 +547,7 @@ class Dataset[T] private[sql](
     }
   }
 
+  // This method intends to be called from PySpark DataFrame
   private[sql] def toExplainString(mode: String): String = {
     mode.toLowerCase(Locale.ROOT) match {
       case "simple" => toExplainString(ExplainMode.Simple)