MF mode means what it says...Manual Focus. That means the camera isn't going to be giving you any assistance in focusing. But...you could let it auto-focus, then switch to manual focusing for 'fine tuning', if desired. Note that leaving the lens set to AF and manually adjusting the focus while still in AF mode after the camera focuses may cause damage to your lens. In general, only the L-series of Canon lenses allow manually adjusting the focus after AF has been made.
As mentioned above, using Live View is a good means of accomplishing MF. But even with LV, manual focus is still 'difficult' to 'really nail it' unless your camera is on a tripod and one has time enough to get it 'just right'. For this reason, I previously considered getting a Katz-Eye focusing screen that replicates the split-ring focusing screen I used in my film-shooting days.
But after some consideration, and, after learning how the Canon AF system works my focusing accuracy with AF significantly improved! Between accurately focusing and understanding depth of field considerations, I've been able to get many outstanding photographs.