It hasn't mentioned the device by name, but the X on the poster indicates that it's going to release a smartphone going by the name Nokia X. And since nearly all numbers below ten have been used up, Nokia perhaps wants to use the "ten" but instead of calling it Nokia 10, why not Nokia X. We're only guessing but there's also a possibility it will have the same fate as the Nokia 3310 which was a reboot of the model from the last decade. From feature phones like the Nokia 3310 (2017) to low-priced Android smartphones like the Nokia 1 and premium handsets like the Nokia 8 Sirocco, HMD has revived the Nokia brand especially in core Asian markets such as India. Not much is known about the phone or its significance.
Also presumably it will not be designed as a competitor to Apple's iPhone X since the rumors make it sound like it will be a mid-ranged handset instead of a flagship phone. The latest reports suggest the company is looking to launch yet another smartphone - called the Nokia X - on April 27 in China.
The Nokia X used to be a family of devices under the old- Nokia which would be running on the Nokia X Platform, a heavily customized Android iteration without Google's suite of services and heavily resembling the layout of the Windows phone.
We're assuming Nokia wanted to give life to its "X".