I don't understand much but the Washington Post does:
http://www.washingtonpost.com/business/technology/new-yahoo-...
* $1 million/year in salary;
* up to $2 million/year in bonuses;
* $14 million in restricted stock & options vesting over three years ($4.7 million/year). Restricted means she won't get these if she leaves before they vest. The real value of these depends on the future value of Yahoo stock
* $30 million retention bonus if she stays 5 years
That's $59 million for the first 5 years ($5M + $10M + $14M + $30M). Yahoo says they expect to pay her a total $100 million over that time period -- they'll award other things on top of these.