"花“ can be used as a noun, which means "flower", as you have already known. And "花“ can also be used as a verb and is similar to "cost/pay/take/spend" in English. It's subject could be person, object or situation. It's object usually is"time" or "money". Eg1. This book cost me $5. 这本书花了我5美元。 Eg2. I paid $5 for this book. / I spent $5 on this book. 我花了5美元买这本书。 Eg3. It took me 2 hours to get to the airport./ I spent 2 hours getting to the airport. 去机场花了我2小时。or you can also translate it into "我花了2小时去机场” and this one sounds more natural in Chinese, though the former one is also correct.

花 also means "spend", like"花钱" ie:他在买书上花了很多钱（he spends a lot of money in buying books）. we sometimes compare "花" to a beautiful girl, "校花"，ie:她是我们学校的校花（she is the most beautiful girl in our school.） .

The "花" here means " takes/uses", it's a verb in Chinese, and here it's no longer a noun which means "flower". If u want to find an equivalence in English, i think u can either say in this way : It 'takes'(=花) him several years to......" hope i've made it clear to u~~

spend, cost