Learn Arabic (Modern Standard): المريضة هنا الآن.

The word المريضة ends with the letter Taa' Marboota (ة), which is the most common feminine marker in Arabic. To make it masculine, you simply drop the ة to get المريض (the male patient).

I noticed the Taa' Marboota (ة) at the end of المريضة sounds like 'a'. Does it ever sound like a 't'?

Yes! When you pause or stop at the end of a word with ة, it makes an 'a' or 'ah' sound. However, if you speak quickly and connect it to the following word in a sentence, it is pronounced as a 't'. Because it is the subject here, connecting it would sound like 'al-mareedhatu'.

Where is the word for 'is' in this sentence?

Arabic doesn't use a word for 'is' or 'are' in simple present-tense sentences. You just place the subject (المريضة) and the information about it (هنا الآن) side by side, and the 'is' is naturally understood.

What is the squiggly mark on top of the first letter in الآن (now)?

That symbol is called a Madda (آ). It represents a long 'aa' sound. It is used to combine an Alif with a glottal stop (أ) and a second stretching Alif (ا) into a single letter, so you don't have to write two Alifs next to each other.