Here are a few options for descriptions for the WordPress post tag “公里” (Traditional Chinese, meaning “kilometer”) depending on the emphasis you want to place:

**Option 1: Simple and Direct**

> 使用這個標籤，了解更多關於距離的測量，特別是公里。
>
> (Use this tag to learn more about the measurement of distance, especially kilometers.)

* **Why this is good:** It’s clear, concise, and directly relates to the term.

**Option 2: Emphasizing Relevance**

> 涵蓋與公里相關的所有文章，包括道路長度、跑步距離、以及其他以公里為單位的測量。
>
> (Covers all articles related to kilometers, including road lengths, running distances, and other measurements expressed in kilometers.)

* **Why this is good:** It provides examples of where the tag might be used, boosting organic search.

**Option 3: Broader Context (if the site deals with travel or transportation heavily)**

> 探索以公里為單位的旅行、道路、運輸和地理文章。探索各種以公里來衡量的資訊。
>
> (Explore articles on travel, roads, transportation, and geography, all measured in kilometers. Discover various information measured in kilometers.)

* **Why this is good:** Places the term in a useful context, encouraging user navigation.

**Option 4: A more educational/detailed approach**

> 公里，即長度的國際單位制 (SI) 測量單位，等於 1000 米。 此標籤的文章將涵蓋與公里度量相關話題，包括距離轉換，地理位置、速度、和其他相關資訊。
>
> (Kilometer, the SI unit of length, equal to 1000 meters. This tag’s articles will cover topics related to kilometer measurements, including distance conversions, geographical locations, speed, and other relevant information.)

* **Why this is good:** Provides background context and can attract users seeking more detailed information, and will do well with search engines looking for that level of specificity.

**How to choose:**

* **Your website’s focus:** Choose the description that best aligns with the main topics of your site.
* **Target audience:** Consider your readers. Are they beginners or more knowledgeable?
* **SEO:** When using the tag on a web page, the more specific options benefit SEO.
* **Word count** Check what’s allowed, or how many characters your theme will display.

I recommend starting with Option 1 or Option 2, then updating/modifying it as needed to best reflect the content on your site.