The term tamahagane (kanji: 玉鋼) means "jewel steel" in English. It is written たまはがね in hiragana. It's pronounced roughly like "tah-mah-ha-gah-neh".
The first kanji, 玉, tama, means “ball” in the generic sense. It can be used, for example, in relation to the eye, rolled-up yarn, or a drop of dew. Oftentimes it is combined with other kanji to refer to something precious: for example, shugyoku (珠玉), which means gem(s). (This word uses the Chinese reading of tama, gyoku.)
Tamahagane, though essential to Japanese sword making, is not a word that enters into everyday conversation. The second kanji, 鋼, hagane, means composite steel; pure steel is called tetsu (鉄). Many Japanese will use the English loanword steel (スチール, suchiiru) instead of hagane. In describing someone with an indomitable spirit, though, they may say that person has hagane no seishin (鋼の精神, “a spirit of steel”).