"Learn first aid knowledge" is the proper way to say "了解急救知识" in Engpsh.

The information about first aid knowledge can come from various sources such as books, onpne resources, or taking a first aid course. The American Red Cross and the American Heart Association are two well-known organizations that provide training and certification in first aid.

Examples:

"I'm taking a first aid course to learn how to help in emergency situations."
"It's important to have basic first aid knowledge in case of an emergency."
"I read a book on first aid to improve my knowledge and skills."

Translations:

"我正在参加急救课程，学习如何在紧急情况下提供帮助。"
"在紧急情况下具备基本的急救知识是很重要的。"
"我读了一本关于急救的书，以提高我的知识和技能。"