Theory:

     He stood on the grass verge by the side of the road and looked over the garden wall at the old house. It hadn’t changed much. The old house built with solid blocks of granite wasn’t altered at all. But there was a new outhouse, and there were fewer trees. He was glad to see that the jackfruit tree still stood at the side of the building casting its shade on the wall. He remembered his grandmother saying:

     ‘A blessing rests on the house where the shadow of a tree falls.’ And so the present owners must also be receiving the tree’s blessings. At the spot where he stood there had once been a turnstile, and as a boy he would swing on it, going round and round until he was quite dizzy. Now the turnstile was gone, the opening walled up. Tall hollyhocks grew on the other side of the wall.
Explanation:
 
The author stood on the grass on the side of  the road and looked at the old house. The house looked almost the same, and it hadn't changed much. The old house was built with granite, and no changes were made to it. But there was a new outhouse and few trees chopped down. But the author was happy to see the jackfruit tree, which was still there at the side of the building. The tree was casing the shade on the wall. The author still remembered whatever his grandmother said.
 
There is a blessing on the house if the shadow of trees falls on the house. So, the author is thinking that the present owner is also getting the blessings from the same jackfruit tree. At the place where the author stood was a mechanical gate consisting of revolving horizontal arms fixed to a vertical post, allowing only one person at a time to pass through and as any young boy, he used to swing on it. He played on it till he was giddy. But now there is no turnstile, that opening was covered with a wall. Tall plants with big flowers had grown on the other side of the wall.
 
Meanings of difficult words:
 
Number
Word
Meanings
1.
Verge Edge.
2.
TurnstileA mechanical gate consisting of revolving horizontal arms fixed to a vertical post, allowing only one person at a time to pass through.
3.
DizzyGiddy.
4.
Hollyhocks A tall Eurasian plant of the mallow family, with large showy flowers.
Reference:
State Council of Educational Research and Training (2018). Term-1 English Standard-9. I Can’t Climb Trees Anymore - Ruskin Bond (Slightly adapted) (pp. 157-160). Published by the Tamil Nadu Textbook and Educational Services Corporation.