Distribution, central tendency and stand deviation.

I cannot wrap my head around this one.

the point in the distribution around which the data are centered is the central tendency and
Used in a sentence: The arithmetic mean is the most commonly used measure of central tendency.

Also connected and annoying me is Dispersion which refers to the extent to which the scores are all tightly clustered around the central tendency. AND The standard deviation is the most commonly used measure of dispersion. I do not get ANY of this.

Question

Distribution, central tendency and stand deviation.

I cannot wrap my head around this one. 

the point in the distribution around which the data are centered is the central tendency and  
Used in a sentence: The arithmetic mean is the most commonly used measure of central tendency. 

Also connected and annoying me is Dispersion which refers to the extent to which the scores are all tightly clustered around the central tendency. AND The standard deviation is the most commonly used measure of dispersion.   I do not get ANY of this.