。
She's been promoted twice since joining this company.
Literal
She [topic-は] this company [to-に] entering [since-てから] 2 times got-promoted.
Three pieces in play. 会社に入る ('to enter a company,' i.e. 'join') is the standard idiom for being hired — Japanese frames employment as 'entering' the company, mirroring the way 会社 functions as a closed organizational unit one is brought into. ~てから ('after / since doing X') sets the time anchor. 二度 ('two times') uses the counter 度 (also 回) for occurrences. 昇進する ('to be promoted, rise in rank') is a Sino-Japanese verb central to corporate vocabulary. Promotions in traditional Japanese companies have historically followed a seniority-based path (年功序列), though merit-based 評価 systems have grown in influence over the past few decades.