Hi and welcome
Basically, your digestive system will break down all carbohydrates into glucose which will then be absorbed into your blood stream making you have high blood sugar levels. Non diabetic people produce insulin which enables that glucose to be removed from the blood and stored and burned as energy in the cells. Type 2 diabetics usually become insulin resistant, so that their body ignores the insulin which is produced and the glucose doesn't get removed from the blood very efficiently. Eating less carbs will therefore enable to body to cope better by not putting too much glucose into the blood stream.
Carbohydrates are both sugars and starches, so you need to avoid or reduce your portion size of foods high in sugar and starch. Sweet stuff like chocolate and cakes and biscuits and sugar and honey and maple syrup etc is the obvious first choice to cut out but fruit in all it's forms (fresh, dried and juiced) is also high in sugar and needs to be restricted. Starchy foods are anything made from grains, like bread, pasta, couscous, rice, breakfast cereals, even otherwise healthy porridge is high in carbs and also root vegetables like potato, sweet potato, parsnips, cassava etc. Reducing your portion size of these foods and the frequency you have them will help significantly too. That may seem like there is not much left to eat but meat, fish, eggs, nuts, cheese and full fat dairy produce are all on the menu along with plenty of leafy green veg like cabbage, spinach, kale. broccoli, cauliflower with lots of cheese is a big favourite with many of us diabetics and salads with generous portion of creamy coleslaw (not the low fat versions which are higher in carbs) Creamy (not low fat) natural Greek yoghurt with berries and mixed seeds and chopped nuts makes a good breakfast and many of us enjoy a coffee made with double cream instead of milk. Another breakfast option I enjoy is a 2 egg omelette with a variety of fillings including mushrooms, onion, peppers, ham, courgettes and cheese.... usually a combination of several of those and served with a side salad and coleslaw.... that keeps me going until tea time without having to worry about lunch.
Many type 2s find it really useful, invaluable even, to self fund a BG meter so that they can test their blood glucose (BG) levels at home and use the info they get from it to adjust their diet to their meter readings. If you are interesting in doing this they are relatively inexpensive (approx. £15) to buy but the on going cost of test strips for them can tot up, so buying a meter which has the cheapest test strips is important. For that reason we recommend the SD Gluco Navii or the Spirit Healthcare Tee2. You get through a lot of test strips in the first couple of months, so make sure to order at least 2 extra pots of test strips when you order. We will advise on a resting regime if you are interested in getting one.
Anyway, hope the above is useful. It is really helpful to keep an honest food diary so that you can see where you are eating most carbs and where you can make reductions. Then if you get a meter, you can log your readings with the meals you have eaten and create a database of meals and portion sized which work for you.