进 combines with directional complements: 进去 (go in, away from speaker), 进来 (come in, toward speaker). This in/out + toward/away pattern is fundamental in Chinese.
Walking radical wrapping the lower-left - the simplified form of 辵, two strokes for legs plus a dot for the head in motion. It marks 进 as a verb of going, in the same family as 退 (retreat), 追 (pursue) and 远 (far away).
井 (jǐng) is the simplified swap-in for traditional 隹 (short-tailed bird), keeping a similar sound and many fewer strokes. The 1956 reformers picked it largely because jǐn/jìn are close in Mandarin. Use 井 here purely as a sound cue - the meaning is all in the 辶 below.
