Israel has been through several monetary reforms since 1948. The reform which engendered this coin applied between 1980 and 1985. The small denomination coin was an agora and the large denomination coin was a sheqel, with 100 agora in 1 sheqel. Sheqalim is the plural form of sheqel.
These coins are made of aluminum bronze and are worth very little today. The monetary reform of 1985 made them obsolete, so they are not even worth face value. The only value they carry is collector value. Collectors will pay a few US dollars for nice specimens without problems such as spots, stains, scratches, or cleanings.
In addition to the 50 sheqalim in our main picture, there is another coin with the same '50' side but, instead of a picture of an ancient coin, the other side shows a stylized portrait of David Ben-Gurion, the main founder and the first Prime Minister of modern Israel. Coins with Ben-Gurion are worth the same as the ancient coin version.