Here are a few options for the WordPress post_tag description, in Traditional Chinese, depending on the level of detail you need:

**Option 1: Simple and Concise**

> 學習 ETF (交易所買賣基金) 的基礎知識及運用。

* **Translation:** Learn the basics and applications of ETFs (Exchange Traded Funds).
* **Best for:** A general overview, good if your content covers a wide range.

**Option 2: More Specific**

> 提供 ETF 投資的入門教學，包括 ETF 的定義、種類、選股策略及風險管理。

* **Translation:** Provides introductory education on ETF investment, including the definition of ETFs, types, stock selection strategies, and risk management.
* **Best for:** More detail, suitable if your content provides a deeper dive into the subject.

**Option 3: Action-Oriented**

> 掌握 ETF 投資的技巧，輕鬆開始您的投資之旅。本標籤提供實用的 ETF 教學資源。

* **Translation:** Master the skills of ETF investment and easily begin your investment journey. This tag provides practical ETF educational resources.
* **Best for:** Encouraging user engagement, and directing users to related content.

**Option 4: Focusing on Beginners**

> 專為新手設計的 ETF 教學，從零開始，逐步了解 ETF 的世界。

* **Translation:** ETF education designed specifically for beginners, starting from zero, step by step to understand the world of ETFs.
* **Best for:** When target audience mainly are beginners.

**How to use this in WordPress:**

1. **Go to your WordPress admin panel.**
2. **Go to “Posts” > “Tags”.**
3. **Find the “ETF教學” tag (or create it if you haven’t).**
4. **In the “Description” field, paste your chosen description.**
5. **Click “Update” or “Save” to save the changes.**

Remember to choose the description that best fits the type of content you are publishing and the audience you are targeting. Good luck!