There are many different types of Hindu symbols or symbolism in Hinduism (if I may). I'll interpret some of the religious symbols (Hinduism only) below -
1) Aum in Hinduism (or What does Aum mean in Hinduism) - Aum (also spelled Om) is one of the main symbols used all over in Hindu religion. The reason that Aum is considered so important and sacred is that, in Hinduism, it basically signifies Moksha or Nirvana or Salvation. It is considered the essence of all and everything. Aum can also refer to Brahman, that is the all pervading, more than the sum of Universe, consciousness and both the beginning and the end of everything. No doubt Aum is the most important sacred and mystical symbol in Hinduism and I've a big article dedicated to it, please read here - What does Aum really mean? (link is coming soon)
2) Swastik in Hinduism - Swastik in Hinduism also carries very deep philosophical significance. Fundamentally Swastik signifies well being, stability and in a way references Brahma (of the Trinity). It's used in almost all Indian (Hindu) homes as a symbol for luck and well being. It's also a common practice to wear it in necklaces and other jewellary. It's mostly drawn in red or yellow but depending on the part of India and occassion various other colors can also be used. To find out the deep philosophical significance attached to the Swastik, please read here - What does Swastik (Swastika) really mean?
3) ShivLing in Hinduism - Shivling (or Lingam) in hinduism is one of the most controversial symbol and you can always find people from different religions picking on Hinduism using Shiv Ling as an (unfair) example. Let me come with it outright - yeah Shivling can very well be a symbol of fertility and as is seen in almost all religious symbols, it's quite common for some symbolisms to have reference to male fertility and the like. But the story doesn't really end there as that is just one severely limited way of understanding the symbolism. In Hinduism, Shivling (Lingam) is seen in various aspects and the aspects (or attributes) mean different things. Please read in more details - What does Shivling (Lingam) really mean? (link is coming soon)
4) Trident in Hinduism - Trident is one of the more complicated symbol in Hinduism because it signifies both good and bad. On one hand Trident one of the weapons held by Lord Shiva and on the other, it has a very deep philosophical significance linking to Trinity in Hinduism (other religions too perhaps). As you can readily see, it's a symbol of war (being a weapon) while also explaining the hindu concept of "oneness in many". I already wrote a lot about this concept in my earlier article about Trinity - Trinity in Hinduism - so I won't repeat it here. But another thing that I'd like to quickly mention is that, in very general terms I also like to interpret Trident as symbolifying a double edged sword! How so? This is kinda very obvious if you are familiar with various hindu mythological stories - Lord Shiva is known to have two completely different personalities, please read more here - Lord Shiva (link coming soon).