Can you help me

I have the 2006 model 206 1.4 hdi, I discovered something behind it today, give it to my ignorance, the car's speed and speed remain constant after pulling the gas in each gear.
For example, in the 1st gear, the vehicle remains stationary at 10 km speed and one speed, even though I do not press the throttle and clutch. The 2nd gear is 15 speeds.

The vehicle is moving thanks to idling speed, and if you leave the clutch without pressing any gas on the start, the vehicle will start to move, but I had never tried it on the move. I think he should stop on the move, if he doesn't, idling speed might be high.

So is it a problem, or how does the car deal with its own feature

It is so in every normal healthy vehicle. what bothers you?

I don't understand grams from the car, so I asked him because I said to my ignorance

All you experience is normal.