Similar to all mobile communication networks, synchronization in the time-frequency domain is a fundamental step that allows a fifth-generation (5G) new radio (NR) user equipment (UE) to properly receive and transmit its data. Due to the wide range of frequencies that are defined for the 5G NR systems, the corresponding synchronization procedure becomes critical and presents many challenges, especially for the applications that would need accurate oscillators to reduce the large values of the frequency offset. In this paper, we present and detail the 5G NR physical layer. Then, we describe the required synchronization procedure for 5G NR. And finally, we present the main challenges and issues within the 5G NR synchronization.