Adel Zedan is correct as to _which mobility exercise would be discussed.
And Sedhunivas Ravi is also correct in the facilitating of normal biomechanics. ( + within the ranges of normal ASL's.)
Depending on the plane of movement, which is determined first by the need of the patient, it could be many different exercises; from squats, to planks, to dips, lateral / low back extensions, pull ups, etc etc.
So, lets first define mobility. Simply put, the ability to perform ADL's without assistance in order to function normally throughout the course of our daily lives, i.e getting out of bed, getting in and out of a vehicle, getting out of a chair, driving, lifting groceries, cooking, cleaning, getting up off the floor, showering, etc etc. Many exercises can assist in these ADL's, and some have more or greater needs than others, depending on lifestyle, work(ing) habits and environments, history of exercise, health history, family needs for others, etc. So therefore, 'an effect of a mobility exercise' would be to promote and live within our daily activities without much difficulty, to specifically: maintain balance, ability to walk without assistance, overall feeling of wellbeing gained from strength, cognitive awareness, confidence, general posture, posture while sitting, etc. I'm sure we can add to this list!
This comes down to many components of the patients history and current health status, for what could be needed or recommended to strengthen their ability to move freely without pain or difficulty of performing most or all ADL's.
When incorporating strength for ADL's, I'd recommend multi-joint exercises, AKA the Big 5. Body Weight or machine Leg Presses, ( & when applicable, limited or versions of squats, and incorporating other balance type / therapeutic exercises, all depends on the patient and current fitness level and what their need and objectives are) , Latissimus Pulldowns, (Pullovers) Rowing, Chest Press, (seated dips) Shoulder Press. Botton line, always vary the exercises...........