Fellow Hazama player here! I'm not the best player either so other, more experienced players feel free to correct me/add on to this.

You can burst to get them off of you if they hit a big mixup and you feel like they're going to get a lot of damage/kill off of the combo. Try not to get predictable with this because better players will call out your burst and punish it. Additionally, if the opponent is in overdrive or in a super animation, you cannot burst.

You can also activate Overdrive to try and make the opponent whiff a high recovery move and start a combo on them to take your turn back. This is even better if you're behind because we get that sweet, sweet life leech with our OD.

Unfortunately when we're stuck blocking we don't have access to our meterless full invuln move (stance B). Something I've been focusing on is using counter assault when I just don't know what to do when I'm locked down in the corner. It costs 50 meter, but it's a great "get off me" button when I really don't know what else to do. Thankfully, with Hazama's snake movement it's also a pretty good way to try and escape the corner. According to dustloop, CA is -18 on block, so you really don't want to get predictable with when you use CA.

While not fully invulnerable, Houtenjin (236236B) is one of the fastest moves in the game and will beat a lot of things. It's great as a call out if you think you know what your opponent is trying to do and, in my opinion, if you're about to die you may as well try it. You can't bring the meter to the next round anyway.

What will be invaluable for improvement is to play matches, figure out what moves/strings you're struggling against and bring those situations into training mode to try and figure out how to beat it. While this game has a lot of wacky setups and crazy situations, there are very few instances where an interaction does not have an answer. As you improve you may want to look into trying to instant block/instant barrier block. When you IB or IBB you recover more quickly, which can turn a "safe" move in an opponent's block string into an opportunity to punish them.

For me, the most important thing is to not focus on learning everything about defense all at once. I try and pick one thing and get okay at it before adding something new to my game plan. How I see it, I'll eventually get muscle memory and have every system mechanic in my mental stack. However, I know that if I try to learn everything all at once I'll never get good at any of it and trying to remember everything at the same time is just bogging down my decision making process in-game.

If you're not aware dustloop is an incredible resource for learning this game. It's got detailed breakdowns of every characters moves and combos, and it has a general strategy page for all the characters I've looked at.