stick to, glutinous, sticky, glue
黏 centers on the quality of being sticky and adhesive: things that cling, glue, or are glutinous. The core idea is a substance that sticks to surfaces or itself.
黏 combines 黍 (millet) and 占, likely as a phonetic component. Millet is glutinous when cooked, so the character originally expressed stickiness through the grain. The exact historical role of 占 is uncertain, but the phono-semantic structure is plausible.
The left side 黍 is millet, a grain that becomes sticky and glutinous when cooked. The right side 占 looks like a divination crack, but here imagine it as a sticky substance oozing out. Together, 黏 is something sticky like glue.
For ネン, picture a sticky nendo (ねんど, clay) sculpture: the first syllable ネン of ねんど cues the reading, and the clay sticks to your hands like 黏.