The acronym ICND stands for Interconnecting Cisco Networking Devices, then number one (1) means that this is the first part of the two parts that the Cisco Certified Network Associate (CCNA) exam has (ICND 1 + ICND 2 = CCNA), and the digits 100-105 represent the exam code issued and standardized by Cisco all over the world. In one sentence, ICND 1 (100-105) exam tests a candidate's knowledge and skills related to network fundamentals, LAN switching technologies, routing technologies, infrastructure services, and infrastructure maintenance.
You can learn more about CCENT certification from https://www.cisco.com/c/en/us/training-events/training-certifications/certifications/entry/ccent.html.
