It means: pick a place to start.
Think of a pseudo random number generator as just a really long list of numbers. This list is circular, it eventually repeats.
To use it, you need to pick a starting place. This is called a "seed".
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…