Update README.md

README.md

@@ -112,7 +112,7 @@ You can easily re-produce following competitive results with minor codes, which
 
 
 
-## Package Overview
+## Overview
 
 <p align="center">
 	<img src="https://github.com/PaddlePaddle/PALM/blob/master/img/architecture.png" alt="Sample"  width="582" height="289">
@@ -121,6 +121,10 @@ You can easily re-produce following competitive results with minor codes, which
 	</p>
 </p>
 
+PaddlePALM is a well-designed high-level NLP framework. You can efficiently achieve **supervised learning, unsupervised/self-supervised learning, multi-task learning and transfer learning** with minor codes based on PaddlePALM. There are three layers in PaddlePALM architecture, i.e., component layer, trainer layer and high-level trainer layer from bottom to top. 
+
+In component layer, PaddlePALM supplies 7 **decoupled** components to achieve a NLP task. Each component contains rich `pre-defined Classes` and a `Base Class`. Pre-defined classes are aiming at typical NLP tasks, and the base class is to help users develop a new Class (based on pre-defined ones or from the base). 
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 | module | illustration | 
 | - | - |
 | **paddlepalm** | an open source NLP pretraining and multitask learning framework, built on paddlepaddle. |