弟子 usually means students. However, in China, ancient China at least, students were treated as if one's children. Here 弟子 refers to the younger generation. 入 means "enter" and 出 means "exist" or "go out". 入則孝 means when inside the house, one should behave with filial piety. 出則弟 means when outside with peers, behave like a younger brother towards the elder brothers.
謹 is cautious (謹慎), 而 means "and". 信 is "trustworthy".
泛愛 is "general love" - like the "love thy neighbor". 眾 is many people. 泛愛眾 is Confucius' "love thy neighbor" spoken at least 400 years before Jesus.
親仁 is "get close to 仁". This is the concept of getting one close to gentlemen, those with wisdom.
行有餘力，則以學文 Practice all these. If there are still energy left, learn the literature. This reinforces the idea that to Confucius, learning is more about building one's character then mere studying literature or text.
All these behavioral suggestions sound abstract. However, we must remember that at Confucius time, there was a very well established set of behavioral rituals (禮) and Confucius was a big supporter of re-establishing the rituals as he saw the ills of the society of his time.
This ends the first chapter of Analects. The next chapter is also on learning.