The reason Spain is usually reported to have a strong economy is not that the country is the world's largest economy; in fact, Spain is not the country with the largest economy in Europe. Currently, the economy of Spain is regarded as the sixth-largest in Europe.
When people are describing Spain to have a strong economy, they are talking about the surprising way the country was able to recover from the financial crisis that the country entered, particularly between 2007-2008. During this period, Spain had the worst economy as it had to battle a serious recession. One of the things that characterized that period is inflation.
Also, millions of people lost their jobs to the financial crisis. However, things started getting better for Spain in 2013 when the country first recorded a positive economic situation. The trade surplus attained during this period allowed the country to reverse the trade deficit that was recorded in the past years.